Luminal stenting

ABSTRACT

A stent delivery system, a core assembly, and methods of operating the same are provided. The delivery system can comprise a catheter and the core assembly. The core assembly can comprise a constraining member, protruding member, a core member, and a stent extending along the core member. The tubular constraining member can be spaced apart from the core member and define a capture area. The protruding member can be disposed along the core member at least partially distal of the capture area. The stent can have a first portion disposed within the capture area and a second portion, distal to the first portion, extending across or over an outer surface of the protruding member so that the protruding member and the constraining member cooperate to inhibit expansion of the first portion of the stent.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/692,021, filed Dec. 3, 2012, which claims the benefit of U.S.Provisional Application No. 61/602,567, filed Feb. 23, 2012, and U.S.Provisional Application No. 61/679,106, filed Aug. 3, 2012, theentireties of which are incorporated herein by reference.

BACKGROUND

Walls of the vasculature, particularly arterial walls, may develop areasof pathological dilatation called aneurysms. As is well known, aneurysmshave thin, weak walls that are prone to rupturing. Aneurysms can be theresult of the vessel wall being weakened by disease, injury, or acongenital abnormality. Aneurysms could be found in different parts ofthe body, and the most common are abdominal aortic aneurysms and brainor cerebral aneurysms in the neurovasculature. When the weakened wall ofan aneurysm ruptures, it can result in death, especially if it is acerebral aneurysm that ruptures.

Aneurysms are generally treated by excluding the weakened part of thevessel from the arterial circulation. For treating a cerebral aneurysm,such reinforcement is done in many ways including: (i) surgicalclipping, where a metal clip is secured around the base of the aneurysm;(ii) packing the aneurysm with small, flexible wire coils (micro-coils);(iii) using embolic materials to “fill” an aneurysm; (iv) usingdetachable balloons or coils to occlude the parent vessel that suppliesthe aneurysm; and (v) intravascular stenting.

Intravascular stents are well known in the medical arts for thetreatment of vascular stenoses or aneurysms. Stents are prostheses thatexpand radially or otherwise within a vessel or lumen to provide supportagainst the collapse of the vessel. Methods for delivering theseintravascular stents are also well known.

In conventional methods of introducing a compressed stent into a vesseland positioning it within in an area of stenosis or an aneurysm, aguiding catheter having a distal tip is percutaneously introduced intothe vascular system of a patient. The guiding catheter is advancedwithin the vessel until its distal tip is proximate the stenosis oraneurysm. A guidewire positioned within an inner lumen of a second,inner catheter and the inner catheter are advanced through the distalend of the guiding catheter. The guidewire is then advanced out of thedistal end of the guiding catheter into the vessel until the distalportion of the guidewire carrying the compressed stent is positioned atthe point of the lesion within the vessel. Once the compressed stent islocated at the lesion, the stent may be released and expanded so that itsupports the vessel.

SUMMARY

At least one aspect of the disclosure provides methods and apparatusesfor delivering an occluding device or devices (e.g., stent or stents) inthe body. The occluding device can easily conform to the shape of thetortuous vessels of the vasculature. The occluding device can be used ina variety of applications. For example, in some embodiments, theoccluding device can direct the blood flow within a vessel away from ananeurysm. Additionally, such an occluding device can allow adequateblood flow to be provided to adjacent structures such that thosestructures, whether they are branch vessels or oxygen demanding tissues,are not deprived of the necessary blood flow.

The delivery of an intravascular stent to a treatment site within thevessel of a patient requires substantial precision. Generally, duringthe implantation process, a stent is passed through a vessel to atreatment location. The stent can be expanded at the treatment location,often by allowing a first end of the stent to expand and thereafterslowly expanding the remainder of the stent until the entire stent hasbeen expanded. The process of initially contacting the vessel wall asthe first end of the stent expands can be referred to as “landing” thestent. The final position of the stent within the vessel is generallydetermined by its initial placement or landing within the vessel. Insome situations, the stent may initially be “landed” in a suboptimallocation within the vessel. Using traditional methods and apparatuses,it may be very difficult for a clinician to reposition the stent withinthe vessel. For example, a clinician may be unable to recapture,collapse, withdraw, or resheath the stent back into the catheter afterthe stent has been partially expanded within the vessel. As such, theinitial landing is critical to successful placement of the stent.

In accordance with an aspect of at least some embodiments disclosedherein is the realization that a medical device delivery system can beconfigured to advantageously enable a clinician to recapture, collapse,withdraw, or resheath a stent within a catheter of the delivery systemafter the stent has been at least partially expanded and landed in thevessel in order to allow the clinician to improve the placement of thestent within the vessel. Further, some embodiments can be configured toenable a clinician to recapture, collapse, withdraw, or resheath thestent even the entire stent has been moved out of the catheter lumen andat least partially expanded against the vessel wall. Moreover, someembodiments can be provided such that the delivery system can engage andretain any braided stent without requiring special-purpose engagementstructures on the stent.

In order to enable a clinician to recapture, collapse, withdraw, orresheath a stent within a delivery system, some embodiments provide fora core assembly that is slidably disposed within a catheter and able tosecure, grip, or engage at least a portion of the stent in order tocontrol movement, deployment, and expansion of the stent. In someembodiments, the core assembly can comprise a constraining member and acore member. The stent can extend over the core member and into a recessformed by the constraining member to engage or secure a portion of thestent.

Optionally, the core assembly can also comprise a protruding portion ormember disposed along the core member. In such embodiments, the stentcan extend over the protruding member and into the recess.

For example, the protruding member and the constraining member cancollectively form a gripping mechanism that engages or secures thestent. The gripping mechanism can engage a proximal or first portion ofthe stent in a collapsed state. The gripping mechanism can provide apress or interference fit between the constraining member and theprotruding member to inhibit expansion of the first end of the stent.The gripping mechanism can enable the stent to be withdrawn, recaptured,retracted, or resheathed into the catheter even after the stent has beenmoved out of the catheter lumen (i.e., the catheter has been fullywithdrawn from the stent) and the stent has at least partially expandedinto apposition with the vessel wall.

The gripping mechanism can enable the core assembly to exert a pushingforce and a pulling force on the stent to adjust its axial positionrelative to the catheter. In some embodiments, the gripping mechanismcan be operative to exert a distal pushing force on the stent todistally advance the stent relative to the catheter until the proximalportion of the stent is distally beyond the distal end of the catheter.Further, the gripping mechanism can also be operative to exert aproximal pulling force on the stent to proximally withdraw the stentinto the catheter when the stent proximal portion is distally beyond thedistal end of the catheter and the stent is at least partially expandedinto apposition with a vessel wall. The gripping mechanism can beconfigured to exert the distal pushing force and the proximal pullingforce on its own without the cooperation of other components orstructures.

In some embodiments, the stent can be secured or engaged between theprotruding member and a distal end of the constraining member (which canbe a sheath) in order to prevent expansion of a proximal or firstportion of the stent. For example, the protruding member and theconstraining member can secure the stent by inducing a variable diameterin the stent between the first portion and the second portion.

In some embodiments, the assembly can be configured such that the coremember has a distal section and a proximal section. The distal sectionof the core member can be a distal tapering section. The core member cancomprise a wire. For example, the distal section of the core member cancomprise a distal tip. The core member distal tip can comprisepolytetrafluoroethylene (PTFE or TEFLON®).

The constraining member can have an inner lumen that is configured toreceive the core member. Further, the constraining member can have adistal portion that can be spaced apart from the core member and canhave a capture area in the lumen. The capture area can be definedbetween the distal portion of the constraining member and the coremember. For example, the capture area can be defined radially between anouter surface of the core member and an inner surface of the tubularconstraining member.

Further, the protruding member can be disposed along the core member atleast partially distal of the capture area. The protruding member canextend radially. Further, the protruding member can have an outersurface. In some embodiments, the protruding member can be disposedaxially between the distal section and the proximal section of the coremember. Furthermore, the stent can have a first portion and a secondportion. The first portion can be a proximal portion that is disposedwithin the capture area. The second portion can be disposed distalrelative to the first portion. The second portion can extend across orover an outer surface of the protruding member so that the protrudingmember and the constraining member cooperate to inhibit expansion of thefirst portion of the stent.

In some embodiments, the core member can extend within the stent lumenand distally beyond the stent distal portion. The protruding member canbe coupled to the core member and be disposed distal of the distalportion of the constraining member within the stent distal portion.

The protruding member can optionally have a generally cylindrical outersurface. For example, the protruding member can comprise an annular ringcoupled to or supported on the core member. The outer surface of theprotruding member can be radially offset from the outer surface of thecore member. Further, the protruding member can be axially spaced apartfrom the distal portion of the constraining member. For example, theouter surface of the protruding member can be radially offset from theinner surface of the constraining member. Furthermore, the outer surfaceof the protruding member can be radially offset from the capture area isdefined by the constraining member and the core member. In someembodiments, the outer surface of the protruding member can be spacedradially between the outer surface of the core member and the innersurface of the constraining member. Furthermore, the second portion ofthe stent can extend over or be supported on the outer surface of theprotruding member.

The protruding member can be disposed at least partially distal of thedistal portion of the constraining member. Further, when the assembly isoriented substantially straight, the protruding member can be configuredsuch that it does not press the stent against the inner surface of thecatheter.

The protruding member can also have an outer surface that is radiallyspaced apart from the inner surface of the catheter such that when theassembly is oriented substantially straight, the protruding member doesnot press the stent against the inner surface of the catheter. Forexample, the protruding member can have a generally cylindrical outersurface. Further, when the assembly is oriented substantially straight,a radial distance between the outer surface of the protruding member andthe inner surface of the catheter can be sized greater than a thicknessof the stent.

Additionally, in some embodiments, the catheter can be provided in orderto form a stent delivery system. The stent delivery system can comprisethe catheter and a core assembly. The catheter can have a distal end. Asnoted above, the core assembly can comprise a tubular constrainingmember, a stent, a core member, and a radially protruding member.

In accordance with some embodiments, the constraining sheath can includea lumen having a cross-sectional inner profile. The protruding membercan have a cross-sectional outer profile that is sized about equal to orgreater than the catheter inner profile. The cross-sectional outerprofile of the protruding member can be sized greater than the catheterinner profile. The stent can extend over the protruding member and intothe constraining sheath such that the stent has a first diameter at thestent's proximal portion and a second diameter at the stent's distalportion, sized greater than the first diameter. Thus, the stent can besecured between the protruding member and the sheath distal end. Inaccordance with some embodiments, the protruding member can be rotatablymounted on the core member, as discussed further herein. Further, theprotruding member and the core member can also be formed from acontinuous piece of material.

Further, a collective outer profile of the stent and the proximal membercan be sized greater than the sheath inner profile. The core member canbe configured to be steerable when the stent is partially expandedwithin a blood vessel by being rotatable relative to the stent and theconstraining sheath. In some embodiments comprising a protruding member,the core member can also be rotatable relative to the protruding member.

The delivery of a stent in a vessel and subsequent expansion of thestent into apposition with the vessel wall can present some challengesin tortuous vessels. For example, during delivery to the treatment site,the delivery system can be configured to comprise one or more rotatablecomponents that allow components of the system to rotate relative toeach other while the delivery system traverses tortuous geometries. Suchflexibility can reduce the overall pushing force required and tend toavoid “whipping” of the stent when it is unsheathed and/or expanded intothe vessel.

For example, in accordance with some embodiments, the delivery systemcan comprise a rotatable core assembly. In such embodiments, the coremember can rotate independently of the protruding member (if present)and/or the stent and the constraining member within the catheter toreduce “whipping” and also to enable steering of the core member, asdiscussed further herein. Such rotatability can facilitate the movementof the core assembly through a catheter of the delivery system so as toreduce the delivery force required to reach the treatment site.

Further, the rotatable core assembly can be configured to allow the coremember to rotate independently of the stent being deployed in thevessel. Thus, the protruding end of the core member can be rotatedwithout disrupting the contact between the vessel wall and the stent.Thus, the clinician can rotate a distal, protruding end of the coremember to preferentially align the protruding end with the adjacentvessel geometry to avoid abrading or perforating the vessel wall whileadvancing the assembly.

For example, after the stent has been moved to the treatment site, thecore member of the delivery system may often include a distallyprotruding end that may be displaced distally as the stent is expandedand released. The distal movement of the protruding end represents ahazard of potentially abrading or perforating a wall of the vessel inwhich the stent is being delivered. Further, when the stent is beingdelivered adjacent to a vessel bifurcation or a sharp turn in thevessel, the vessel geometry, such as an apex of the bifurcation, may beparticularly difficult to avoid.

In some embodiments, a core assembly can be rotatable by providing aprotruding member that is rotatably mounted on the core member. In suchembodiments, the core member can be rotatably coupled relative to theprotruding member thereof in order to allow the core member to rotaterelative to the protruding member, the constraining member, and thestent. For example, the protruding member can comprise an annularcomponent that is rotatably mounted on the constraining mechanism.

Thus, a steerable or rotatable stent delivery system can be provided.Embodiments of such a system can comprise a microcatheter, a coremember, and a stent. The microcatheter can have a distal end configuredto be inserted into a blood vessel. The core member can extend withinthe microcatheter. Further, the core member can have a distal portionand an intermediate portion proximal to the distal portion. The stentcan extend along the intermediate portion. Further, the core member canbe configured to be steerable when the stent is partially expandedwithin the vessel by being rotatable relative to the stent and themicrocatheter. Accordingly, the core member can be steerable to avoiddislodging of the stent from the vessel wall and abrading or perforationof the vessel wall.

In some embodiments, the system can also comprise a protruding member.The protruding member can be positioned along the core member in theintermediate portion and be rotatably coupled to the core member. Insome embodiments, the core member can comprise an arcuate tip thatextends distal of the protruding member. The core member distal portioncan comprise the arcuate tip, which can extend transverse to alongitudinal axis of the microcatheter. The arcuate tip can extendtransverse to or bends away from a central axis of the microcatheterlumen. The microcatheter can be either as the constraining sheath orcatheter discussed herein.

In some embodiments, the distal portion can comprise an assemblyincluding the distal cover and a distal tip structure. The tip structurecan be rotatably or fixedly coupled relative to the core member.Further, the distal cover can be coupled to the tip structure.

The distal tip structure can comprise at least one member or componentthat can be carried by the core member. In some embodiments, the atleast one member can be oriented generally transverse or parallel to thecore member. For example, the tip structure can comprise a coil(s), acircumferentially-extending band(s) of material, a clamp(s), and/orother structures that can pass smoothly within a vessel at the distalportion of the core member. Further, the at least one member cancomprise at least one segment of the coil or other structure.

In some embodiments of a rotatable core assembly, the distal portion ofthe core member can comprise a distal tip structure and/or distal coverthat can be rotatably coupled to the core member. Thus, a rotatableinterconnection between the distal tip structure and/or distal cover andthe core member can allow the core member to rotate freely of the distaltip structure and/or distal cover, thus avoiding transmission of anyrotational or torsional stresses to the stent via the distal cover. Forexample, the distal cover can be configured to rotate about the coremember. Further, the second end of the distal cover can be rotatablycoupled with respect to the core member. Furthermore, the stent can beconfigured to rotate about the core member at least in part by virtue ofthe rotatable coupling of the distal cover.

In operation, after the catheter has been positioned in the bloodvessel, the stent can be partially expanded into apposition with a wallof the vessel. The clinician can rotate a distalmost curvilinear tip ofthe core member of the delivery system. The tip can be configured tobend away from a central longitudinal axis of the core member. Thus,when rotated, the core member's curvilinear tip can rotate relative tothe stent and the constraining member. Further, as noted above in someembodiments comprising a protruding member, the core member can berotatably coupled to the protruding member. In such embodiments, whenrotated, the core member's curvilinear tip can rotate relative to thestent, the protruding member, and the constraining member. Accordingly,the clinician can align the curvilinear tip with a path of the vessel toavoid abrading or perforating the vessel wall. Thereafter, the coremember can be advanced distally to guide the core member along a path ofthe vessel. Such methods and systems can be particularly useful when thegeometry of the vessel includes a bifurcation or a sharp turn in thevessel, especially to guide the tip of the core member away from an apexof a bifurcation adjacent to the treatment site.

In accordance with yet other embodiments disclosed herein, the coreassembly can be configured to comprise a distal portion that enables adistal or leading end of the core assembly and stent to be lubriciouslypassed through a catheter while also facilitating the resheathing of thedistal portion within the catheter, as desired.

In some embodiments in which the distal portion comprises a distalcover, the distal cover can be coupled to the core member and at leastpartially surround or cover the stent distal portion. Thus, when thecore assembly is slidably disposed within the catheter, the distal covercan be positioned between, for example, radially between, the stentdistal portion and the catheter inner wall.

In embodiments that comprise a distal cover, the distal cover cancomprise a flexible material that can extend anteriorly over at least aportion of the stent in order to provide a lubricious interface betweenthe core assembly and an inner surface of the catheter lumen.

The distal cover can be attached are coupled to the distal tip structureor core wire using a variety of attachment means. According to someembodiments, the distal cover can be coupled to the distal tip structureby virtue of forming an enclosure that encloses at least one member ofthe distal tip structure. For example, the distal cover can form anenclosure that encloses the tip structure, e.g., at least one coilsegment, by virtue of at least partially wrapping around the segment.

The distal cover can comprise one or more elongate strips of material.For example, the distal cover can comprise a pair of a longitudinallyextending elongate strips that at least partially cover or surround thedistal portion of the stent. In some embodiments, the distal covercomprises no more than two elongate strips of material. In someembodiments, the distal cover can be cut from a tubular member such thata plurality of elongate strips are formed and interconnected by anannular ring of material.

Further, the distal cover can be configured to allow the distal end ofthe stent to expand when the distal end of the stent is moved axiallybeyond a distal end of the catheter. In some embodiments, the distalcover can be configured to provide little or no constraining force orotherwise inhibit the expansion of the distal end of the stent.

The distal cover can be configured to flip, evert, or otherwise movefrom one position to another. In accordance with some embodiments, thedistal cover can comprise a first end and a second end. The first endcan be a free first end, and the second end can be coupled to the distalportion. The distal cover can have a first, delivery, or proximallyoriented position, orientation, or configuration in which the first endextends proximally relative to the core member distal portion and atleast partially covers or surrounds the stent distal portion. The distalcover can be movable from the first, delivery, or proximally orientedposition, orientation, or configuration, in which the free first end islocated proximally relative to the second end, to a second, resheathing,everted, or distally oriented position, orientation, or configurationwherein the first end is positioned distally relative to the second end.Thus, the distal cover can enable the core assembly to be easilywithdrawn or received into the catheter lumen. Further, the distalportion of the constraining member can be axially spaced apart from adistal portion of the stent in both the delivery position orconfiguration and the resheathing position or configuration.

In some embodiments, the distal cover can extend anteriorly relative tothe attachment point of the distal cover and/or the distal tip structurewhile the stent is being delivered to the treatment site. For example,the distal cover can extend along at least about one third of the stent.Further, the distal cover can be everted to extend distally relative tothe attachment point of the distal cover and/or the distal tip structureafter the distal end of the stent has been expanded.

Various methods for operating the core assembly and the stent deliverysystem are also provided. Initially, in order to position the stentdelivery system within a vessel of a patient, a clinician can firstposition a catheter in the vessel. The catheter can have a lumen thatdefines an axis extending between a proximal end and a distal end, suchthat the catheter distal end is at a treatment site. The clinician canposition a core assembly within the catheter lumen. The clinician canalso advance the core assembly distally within the catheter. Thereafter,various implementations of methods can be performed using one or more ofthe core assemblies disclosed herein.

For example, operation of an embodiment of a stent delivery system canbe performed by first moving a core assembly through a catheter to atreatment site. A constraining member of the assembly can be configuredto receive a portion of a stent proximal portion, such that the stent issecured between a distal end of the constraining member and a proximalend of a protruding member in a delivery position. The catheter can beproximally retracted relative to the core assembly until theconstraining member distal end and the stent proximal portion arepositioned distally beyond a catheter distal end while maintaining thestent proximal portion in the delivery position or configuration withthe core member distal section extending distally relative to the stent.Further, a distal portion of the stent can be expanded into appositionwith a vessel wall while maintaining the stent proximal portion in thedelivery position.

Thus, in accordance with some embodiments, the core assembly can beproximally withdrawn into the catheter to resheath the stent within thecatheter after the distal portion of the stent has already beenexpanded. When using a self-expanding stent, a distal portion of thestent can expand automatically when the distal portion of the stentexits the catheter. Further, in order to expand a distal portion of thestent, a distal cover, which at least partially surrounds or covers adistal portion of the stent, can be unfurled.

Additionally, in some embodiments in which the core assembly comprisesthe distal cover, the distal cover can extend in a proximal direction toat least partially cover a distal portion of a stent supported on thecore assembly. At least a portion of the distal cover can be interposedbetween the stent distal portion and the inner wall. The stent distalportion can be distally advanced beyond the catheter distal end topermit expansion of the stent distal portion. The core assembly can thenbe withdrawn into the lumen, such that the distal cover is retractedinto the lumen in an everted configuration and oriented distally fromthe core assembly.

Further, in some embodiments, in which the core assembly has (i) anelongate member comprising a distal end, (ii) an intermediate portioncomprising a distal end positioned at the member distal end, (iii) astent having a distal portion and being carried by the intermediateportion, and (iv) a distal cover coupled to the member distal end, thecore assembly can be positioned within the lumen such that theintermediate portion distal end is positioned axially adjacent thecatheter distal end with at least a portion of the distal coverextending in a space within the lumen radially between the intermediateportion distal end and the catheter distal end. The clinician can thendistally advance the core assembly relative to the catheter to permitexpansion of the stent distal portion. The expansion can urge the distalcover away from the intermediate portion. Finally, the clinician canproximally withdraw the core assembly into the catheter such that theintermediate portion is positioned axially adjacent to the catheterdistal end with the distal cover positioned outside of the space. Insome embodiments, during proximal withdrawal of the core assembly intothe catheter, the distal cover can be positioned outside of the space toprovide a clearance between the intermediate portion and the catheter.

Furthermore, in some embodiments, the core assembly can have (i) adistal portion, (ii) a distal cover extending from the distal portion,and (iii) a stent having a distal portion and being carried by the coreassembly. The core assembly can be advanced within the catheter suchthat the distal cover extends proximally from the distal portion and anannular space between the distal portion and the catheter. The cliniciancan distally advance the core assembly relative to the catheter topermit expansion of the stent distal portion. The expansion can urge thedistal cover radially away from the core assembly. Further, the coreassembly can be proximally withdrawn into the catheter such that thedistal cover extends distally through the annular space. In suchembodiments, during proximal withdrawal of the core assembly into thecatheter, the distal cover can extend distally through the annular spaceto provide a clearance between the catheter and an intermediate portionof the core assembly proximal to the distal cover.

Further, embodiments of the methods can further comprise advancing thecore assembly distally within the catheter such that a proximal end ofthe stent is positioned outside of the lumen. The method can beperformed to further comprise the step of releasing the stent at thetreatment site within the vessel. The method can also compriseproximally withdrawing the core assembly from the lumen whilemaintaining the catheter distal end in place at the treatment site.Additionally, a second core assembly can be inserted into the lumen. Thesecond core assembly can be configured to deliver a second stent at thetreatment site.

In some embodiments of the methods, proximally withdrawing the coreassembly can comprise everting a free first end of the distal cover froma proximally oriented position to a distally oriented position. Further,the distal cover can be coupled to the core assembly at a distal coversecond end, and the first end can be positioned distally relative to thesecond end when the distal cover is everted.

In accordance with yet other embodiments of the methods, the distalcover can comprise a plurality of elongate flexible strips having firstends and second ends. The second ends can be coupled to the coreassembly. In such embodiments, proximally withdrawing the core assemblycan comprise everting the distal cover, such that the first ends aredrawn together distal to the second ends.

In accordance with some implementations, a steerable stent deliverysystem is provided that can comprise a microcatheter, a core member, aprotruding member, and a stent. The microcatheter can have a distal endconfigured to be inserted into a blood vessel. The core member canextend within the microcatheter. The core member can have a distalportion and an intermediate portion proximal to the distal portion. Theprotruding member can be positioned along the core member in theintermediate portion. The protruding member can be rotatably coupled tothe core member. The stent can extend over the protruding member andalong the intermediate portion. Further, the core member can beconfigured to be steerable when the stent is partially expanded withinthe vessel by being rotatable relative to the stent and themicrocatheter.

The core member can be steerable to avoid (i) dislodging of the stentfrom the vessel wall and (ii) perforation of the vessel wall. Further,the microcatheter can comprise a lumen having a central axis, and thecore member distal portion can comprise an arcuate tip that extendstransverse to the axis. Furthermore, the system can further comprise aconstraining member disposed along the core member and a distal portion(i) spaced apart from the core member and (ii) having a capture area.The protruding member can be positioned adjacent to a distal end of theconstraining member. The stent can have (i) a first portion disposedwithin the capture area and (ii) a second portion, distal to the firstportion, supported on an outer surface of the protruding member tosecure the stent between the protruding member and the constrainingmember.

The system can also comprise a distal cover extending proximally fromthe core member distal portion and interposed between an outer surfaceof the stent and an inner surface of the microcatheter. The system canalso comprise a distal tip attached to the core member at the distalportion thereof, and the distal cover can be attached to the distal tip.The distal tip can be rotatably coupled to the core member. The distaltip and the core member can be formed from a continuous piece ofmaterial.

The system can further comprise an actuator attached to a proximalportion of the core member, and the actuator can be configured to impartrotation the core member.

Methods of operating a steerable stent delivery system can be provided.According to aspects of some embodiments disclosed herein, the deliverysystem can comprise a tubular constraining member, a core member or wirehaving a central longitudinal axis, a annular protruding memberrotatably coupled to the core wire, and a distalmost curvilinear tipthat bends away from the axis. The stent can extend over the protrudingmember and be secured between the protruding member and the constrainingmember, such that the core wire is rotatable relative to the stent, theprotruding member, and the constraining member. In accordance with someaspects of methods disclosed herein, a clinician can position a distalend of a catheter of the delivery system in a blood vessel. Theclinician can partially expand a stent of the delivery system intoapposition with a wall of the blood vessel. The clinician can thenrotate the tip relative to the stent, the protruding member, and theconstraining member. For example, the clinician can rotate the tip untilit achieves a desired orientation relative to the blood vessel geometry.Thereafter, the clinician can advance the core wire distally to guidethe core wire along a path of the vessel.

In some embodiments, when the clinician rotates the tip, the relativemovement between the core wire and the stent can avoid dislocation ofthe stent from the vessel wall. Further, in some embodiments, theclinician can advance the tip toward a vessel bifurcation. Furthermore,in some embodiments, the method can be implemented wherein rotating thetip comprises directing the tip in a direction away from an apex of thebifurcation.

In accordance with some implementations, a stent delivery system can beprovided that comprises a constraining sheath, a core member, aprotruding member, and a stent. The constraining sheath can have adistal end and a lumen having a cross-sectional inner profile.

The stent can have (i) a proximal portion disposed within the sheathlumen and (ii) a distal portion extending over an outer surface of theprotruding member. In some embodiments, the distal portion can be atleast partially covered at the core member distal region. The stent canhave a first diameter at the proximal portion and a second diameter atthe distal portion, sized greater than the first diameter, such that thestent is secured between the protruding member and the sheath distalend.

In some embodiments, the core member can have a distal region and extendwithin the sheath lumen. The protruding member can be rotatably mountedon the core member. For example, the protruding member can be rotatablymounted on the core member proximal to the distal region. The protrudingmember can have a cross-sectional outer profile that is sized aboutequal to or greater than the catheter inner profile. In someembodiments, the protruding member can have a cross-sectional outerprofile that is sized greater than the catheter inner profile.

The stent can be secured between the protruding member and the sheathdistal end to prevent expansion of the stent first portion. Further, acollective outer profile of the stent and the proximal member can besized greater than the sheath inner profile. The core member can beconfigured to be steerable when the stent is partially expanded within ablood vessel by being rotatable relative to the stent, the protrudingmember, and the constraining sheath. The protruding member outer profilecan be generally cylindrical. The protruding member can comprise atubular structure fitted over the core member. The constraining sheathcan comprise a distal portion (i) spaced apart from the core member and(ii) having a capture area. Optionally, an outer surface of theprotruding member can be radially offset from the capture area. Thestent can be engaged between the protruding member and the constrainingsheath in a press fit to prevent expansion of the stent first portion.The stent can be engaged between the protruding member and theconstraining sheath in an interference fit to prevent expansion of thestent first portion.

Additional features and advantages of the subject technology will be setforth in the description below, and in part will be apparent from thedescription, or may be learned by practice of the subject technology.The advantages of the subject technology will be realized and attainedby the structure particularly pointed out in the written description andembodiments hereof as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the subject technology.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide furtherunderstanding of the subject technology and are incorporated in andconstitute a part of this specification, illustrate aspects of thedisclosure and together with the description serve to explain theprinciples of the subject technology.

FIG. 1 is a schematic, partial cross-sectional view of a stent deliverysystem, according to one or more embodiments disclosed.

FIG. 2 is a schematic side view of a core assembly of the system shownin FIG. 1 with a stent mounted thereon, according to some embodiments.

FIG. 3A is a schematic side cross-sectional view of a proximal portionof the core assembly shown in FIG. 2, according to some embodiments.

FIG. 3B is a schematic side cross-sectional view of a proximal portionof the core assembly shown in FIG. 2, according to some embodiments.

FIG. 4A is a schematic side cross-sectional view of an embodiment of acore assembly.

FIG. 4B is a schematic side cross-sectional view of another embodimentof a core assembly.

FIG. 5A is a schematic side cross-sectional view of a distal portion ofthe core assembly shown in FIG. 2, according to some embodiments.

FIG. 5B is a schematic side cross-sectional view of another embodimentof a distal portion of the core assembly shown in FIG. 2.

FIG. 5C is a rear perspective view of yet another embodiment of a distalportion of the core assembly shown in FIG. 2.

FIG. 6 is a schematic side view of the core assembly of the system ofFIG. 1 wherein the stent is not shown, according to some embodiments.

FIG. 7A is a schematic, partial cross-sectional view of the system ofFIG. 1, in which a stent has been initially expanded against a vesselwall and a distal cover of the system is disengaged, according to someembodiments.

FIG. 7B is a schematic, partial cross-sectional view of the system ofFIG. 1, in which the distal cover has migrated to an everted position,according to some embodiments.

FIG. 7C is a schematic, partial cross-sectional view of the system ofFIG. 1, in which the distal cover has migrated to another evertedposition, according to some embodiments.

FIG. 8 is a schematic, partial cross-sectional view of the system ofFIG. 1, in which the stent has been partially expanded against thevessel wall and moved outside of a catheter lumen, according to someembodiments.

FIG. 9 is a schematic, partial cross-sectional view of the system ofFIG. 1, in which the stent has been retracted or resheathed into thecatheter lumen after initial expansion of the stent, according to someembodiments.

FIG. 10 is a schematic, partial cross-sectional view of the system ofFIG. 1, in which the stent and a distal tip assembly of the coreassembly have been retracted or resheathed into the catheter lumen afterinitial expansion of the stent, according to some embodiments.

FIG. 11 is a schematic, partial cross-sectional view of the system ofFIG. 1, in which the stent has been expanded and released from the coreassembly into apposition with the vessel wall, according to someembodiments.

FIG. 12 is a schematic, partial cross-sectional view of the system ofFIG. 1, in which the core assembly has been retracted or received intothe catheter lumen after releasing the stent, according to someembodiments.

FIG. 13A is a schematic, partial cross-sectional view of a stentdelivery system positioned at a treatment site adjacent to a vesselbifurcation.

FIG. 13B is a schematic, partial cross-sectional view of the stentdelivery system and the treatment site shown in FIG. 13A, in which adistal portion of a core member of the stent delivery system has beenrotated to avoid abrading or perforation of a vessel wall, according tosome embodiments.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth to provide a full understanding of the subject technology. Itshould be understood that the subject technology may be practicedwithout some of these specific details. In other instances, well-knownstructures and techniques have not been shown in detail so as not toobscure the subject technology.

Described herein are various embodiments of stent delivery systemsexhibiting small cross-sections which are highly flexible and canprovide advantages such as allowing the clinician to recapture,collapse, withdraw, or resheath and reposition a partially expandedstent, avoid vessel abrasions or perforations during placement, placeseveral stents (e.g., “telescoping”) without removing the microcatheter,and/or avoid torsional stress and “whipping” that can occur duringdelivery of the stent. Various other features and advantages ofembodiments are discussed and shown herein.

In some embodiments, a stent delivery system is provided that caninclude a core assembly and an introducer sheath and/or catheter. Thecore assembly can comprise a stent extending over, carried, or supportedby a core member. The core member can comprise a core wire. The coreassembly can be movable within the introducer sheath and/or catheter inorder to deliver the stent to a predetermined treatment site, such as ananeurysm, within the vasculature of a patient. Thus, prior to deliveryof the stent, the catheter can be configured to be introduced andadvanced through the vasculature of the patient. The catheter can bemade from various thermoplastics, e.g., polytetrafluoroethylene (PTFE orTEFLON®), fluorinated ethylene propylene (FEP), high-densitypolyethylene (HDPE), polyether ether ketone (PEEK), etc., which canoptionally be lined on the inner surface of the catheter or an adjacentsurface with a hydrophilic material such as polyvinylpyrrolidone (PVP)or some other plastic coating. Additionally, either surface can becoated with various combinations of different materials, depending uponthe desired results.

The stent can take the form of a vascular occluding device, arevascularization device and/or an embolization device. In someembodiments, the stent can be an expandable stent made of two or morefilaments. The filaments can be formed of known flexible materialsincluding shape memory materials, such as nitinol, platinum andstainless steel. In some embodiments, the filaments can be round orovoid wire. Further, the filaments can be configured such that the stentis self-expanding. In some embodiments, the stent can be fabricated fromplatinum/8% tungsten and 35N LT (cobalt nickel alloy, which is a lowtitanium version of MP35N alloy) alloy wires. In other embodiments, oneor more of the filaments can be formed of a biocompatible metal materialor a biocompatible polymer.

The wire filaments can be braided into a resulting lattice-likestructure. In at least one embodiment, during braiding or winding of thestent, the filaments can be braided using a 1-over-2-under-2 pattern. Inother embodiments, however, other methods of braiding can be followed,without departing from the scope of the disclosure. The stent canexhibit a porosity configured to reduce haemodynamic flow into and/orinduce thrombosis within, for example, an aneurysm, but simultaneouslyallow perfusion to an adjacent branch vessel whose ostium is crossed bya portion of the stent. As will be appreciated, the porosity of thestent can be adjusted by “packing” the stent during deployment, as knownin the art. The ends of the stent can be cut to length and thereforeremain free for radial expansion and contraction. The stent can exhibita high degree of flexibility due to the materials used, the density(i.e., the porosity) of the filaments, and the fact that the ends arenot secured.

Information regarding additional embodiments, features, and otherdetails of the occlusion devices or stents, methods of use, and othercomponents that can optionally be used or implemented in embodiments ofthe occlusion devices or stents described herein, can be found inApplicants' co-pending applications U.S. patent application Ser. Nos.12/751,997, filed on Mar. 31, 2010; 12/426,560, filed on Apr. 20, 2009;11/136,395, filed May 25, 2005; 11/420,025, filed May 24, 2006;11/420,027, filed May 24, 2006; 12/425,604, filed Apr. 17, 2009;12/896,707, filed Oct. 1, 2010; 61/483,615, filed May 6, 2011;61/615,183, filed Mar. 23, 2012; 61/753,533, titled Methods andApparatus for Luminal Stenting, filed on Jan. 17, 2013; 13/614,349,titled Methods and Apparatus for Luminal Stenting, filed on Sep. 13,2012; and 13/664,547, titled Methods and Apparatus for Luminal Stenting,filed on Oct. 31, 2012; the entireties of each of which are incorporatedherein by reference.

For example, in some embodiments, the occluding device or stent may be aself-expanding stent made of two or more round or ovoid wire filaments.The filaments may be formed of flexible materials includingbiocompatible metals or alloys, such as nitinol, platinum,platinum-tungsten, stainless steel, cobalt-chromium, or cobalt-nickel.In some embodiments, the occluding device or stent can be fabricatedfrom a first plurality of filaments of platinum/8% tungsten and a secondplurality of filaments of 35N LT (cobalt nickel alloy, which is a lowtitanium version of MP35N alloy). In other embodiments, one or more ofthe filaments can be formed of a biocompatible metal material or abiocompatible polymer.

The core member can be sufficiently flexible to allow the stent deliverysystem to bend and conform to the curvature of the vasculature as neededfor axial movement of the stent within the vasculature. The core membercan be made of a conventional guidewire material and have a solidcross-section. Alternatively, the core member can be formed from ahypotube. The material used for the core member can be any of the knownguidewire materials including superelastic metals or shape memoryalloys, e.g., nitinol. For example, the core member, along its length orat least at its distal end or tip, can comprise polytetrafluoroethylene(PTFE or TEFLON®). Alternatively, the core member can be formed ofmetals such as stainless steel.

In one or more embodiments, the stent delivery system can exhibit thesame degree of flexion along its entire length. In other embodiments,however, the stent delivery system can have two or more longitudinalsections, each with differing degrees of flexion or stiffness. Thedifferent degrees of flexions for the stent delivery system can becreated using different materials and/or thicknesses within differentlongitudinal sections of the core member. In another embodiment, theflexion of the core member can be controlled by spaced cuts (not shown)formed within the core member. These cuts can be longitudinally and/orcircumferentially spaced from each other.

In some embodiments, the core assembly can secure, grasp, or engage in aproximal end of the stent to facilitate recapture, retraction,withdrawal, or resheathing of the stent into the catheter lumen. Thecore assembly can optionally comprise a constraining member orcontainment sheath. Further, the core member of the core assembly canoptionally comprise at least one protruding member or variable diameterportion disposed along the length of the core member that can cooperatewith the constraining member or containment sheath to secure, grasp, orengage the stent in a press, friction, or interference fit. Accordingly,in some embodiments, the constraining member and the protruding membercan cooperate to form a gripping mechanism that engages a proximal orfirst portion of the stent. The gripping mechanism can secure or engagethe first portion of the stent in a collapsed or expanded state.

For example, the containment sheath can be movable relative to the coremember and configured to receive a proximal or first end of the stent.When assembled, the stent can extend over the core member with aproximal portion of the stent extending over a variable diameter portionof the core member and the proximal end of the stent received axiallywithin a distal end of the containment sheath. The distal end of thecontainment sheath and the variable diameter portion of the core membercan be axially spaced or offset from each other. The spacing of thedistal end of the containment sheath and the variable diameter portionof the core member can be configured to create a press, friction orinterference fit with the stent extending therebetween in order tosecure, grasp, retain, or engage the proximal portion of the stent.Accordingly, the variable diameter portion or protruding member of thecore member can cooperate with the containment sheath or constrainingmember to inhibit expansion of the proximal or first portion of thestent.

In some embodiments, the proximal portion of the stent can be secured,grasped, retained, maintained, or engaged in a collapsed or unexpandedstate. Further, in some embodiments, the proximal portion of the stentcan be secured or engaged in a manner that induces a change in diameterin the proximal portion of the stent. For example, the proximal portionof the stent can extend over or be seated on the variable diameterportion of the core member while a section of the proximal portion ofthe stent is disposed axially within the distal end of the containmentsheath, which section is urged to a smaller diameter size than thediameter size of the proximal portion extending over or seated on thevariable diameter portion of the core member. Furthermore, in someembodiments, the distal end of the containment sheath can abut adiameter-changing portion of the stent to thereby create a press,friction, or interference fit.

In some embodiments, the variable diameter portion of the core membercan comprise one or more steps and/or axially extending protrusions. Thevariable diameter portion can be formed as an integrated structure ofthe core member (e.g., the core member and the variable diameter portioncan be formed from a single, continuous piece of material). However, thevariable diameter portion can be a separate structure that is placedonto, coupled, and/or attached to the core member. Further, in someembodiments, the variable diameter portion can be fixed relative to thecore member. In other embodiments, the variable diameter portion can berotationally and/or longitudinally movable relative to the core member.

For example, the variable diameter portion can comprise a cylindricalstructure or support member that is configured to rotate about the coremember, but can be fixed in a longitudinal position (or have a limitedrange of longitudinal movement) relative to the core member.Accordingly, in some embodiments, the variable diameter portion canfacilitate rotation of the stent. Typically, during delivery of thestent to the treatment site, passing through tortuous vessels can inducea torsional stress in the delivery system and/or stent. However, in someembodiments, a rotatable (preferably cylindrical) variable diameterportion can support the stent and allow the stent to rotate about thecore member, thereby alleviating torsional stresses during delivery.Such a rotatable variable diameter portion can thus reduce or eliminatethe tendency of the stent to “whip” when released or expanded.“Whipping” is the rapid, rotational unwinding that sometimes occurs whenthe stent is released, due to the release of torsional forces that havebeen exerted on the stent during delivery. Further, the rotatablevariable diameter portion can also allow the core assembly to exhibitgreater flexibility during delivery of the stent to the treatment site.

Further, the securement or engagement of the proximal portion of thestent can allow a clinician to exert a distal pushing force on the stentto distally advance the stent relative to the catheter, as well as toexert a proximal pulling force on the stent to proximally withdraw orretract the stent into the catheter, even after the entire stent hasbeen moved distally beyond a distal end of the catheter and partiallyexpanded into apposition with a vessel wall.

Indeed, after navigating the core assembly along the length of thecatheter to the treatment site within the patient, the stent can bedeployed from the catheter in a variety of ways. In one embodiment, thecatheter can be retracted while maintaining the position of the coremember to expose the distal end of the core member and the distal end ofthe stent. While this is being done, the stent can be engaged in acollapsed state at least at the proximal end or portion thereof. In someembodiments, the stent can be engaged at both the proximal and distalends or portions thereof while the catheter is being retracted.

For example, the catheter can be proximally withdrawn relative to thecore assembly, thereby exposing a distal tip assembly of the coreassembly. The distal portion or assembly of the core assembly cancomprise a distal tip structure and/or a flexible distal cover.

The distal tip structure can comprise at least one member or componentthat can be carried by the core member. In some embodiments, the atleast one member can be oriented generally transverse or parallel to thecore member. For example, the tip structure can comprise a coil(s), acircumferentially-extending band(s) of material, a clamp(s), and/orother structures that can pass smoothly within a vessel at the distalportion of the core member. Further, the at least one member cancomprise at least one segment of the coil or other structure.

In some embodiments, the distal cover can at least partially cover orsurround a distal end of the stent extending over an intermediateportion of the core assembly in a first, wrapping, delivery, orpre-expansion position. For example, in this position, the core assemblycan be positioned axially within the lumen of the catheter such that thedistal end of the stent is positioned axially adjacent to the distal endof the catheter with at least a portion of the distal cover extending ina space within the catheter lumen radially between the distal end of thecatheter and at least one of the stent or the intermediate portion ofthe core assembly. The distal cover can extend proximally from thedistal portion or assembly and the space between the distal portion andthe catheter. Further, in some embodiments, at least a portion of thedistal cover can be positioned outside of a space radially between thedistal tip structure of the core assembly and the catheter. Accordingly,in some embodiments, the distal cover can comprise one or more strips ofa flexible and/or lubricious material that can be positioned radially inbetween portions of the distal end of the stent and the inner surface ofthe catheter to reduce sliding friction between the core assembly andthe catheter.

However, as the distal end of the stent is unsheathed or moved beyondthe distal end of the catheter lumen, the distal end of the stent canbegin expanding and thereby urge the distal cover from the first,wrapping, delivery, or pre-expansion position or configuration to asecond, unfurled, expanded, resheathing, or everted position orconfiguration. As the distal cover moves to the everted position orconfiguration, the distal end of the stent can be expanded intoapposition with the vessel wall. If the stent is “landed” at the correctposition within the vessel, the remainder of the stent can beunsheathed, expanded, and released into the target vessel.

However, in accordance with some embodiments, after the stent has beenpartially expanded and even if the stent has been fully unsheathed ormoved beyond a distal end of the catheter, the stent delivery system canallow the clinician to recapture, collapse, withdraw, or resheath thestent into the catheter and later deploy, expand or unsheath the stentagain from the catheter. As noted above, some embodiments allow thestent to be proximally secured, grasped, or engaged by the core assemblyin order to both exert a distal pushing force on the stent and to exerta proximal pulling force on the stent. Thus, even when the stent hasbeen fully unsheathed or moved beyond a distal end of the catheter, aproximal end of the stent can remain secured, grasped, or engaged withthe core assembly to allow the stent to be retracted or withdrawnproximally into the catheter until the entire length of the stent hasbeen resheathed into the catheter. In accordance with some embodiments,the distal cover can be retracted or withdrawn into the catheter in itssecond, unfurled, expanded, resheathing, or everted position orconfiguration.

For example, while the stent is being retracted or withdrawn back intothe catheter, the distal cover can be positioned outside of the spaceradially between the catheter and at least one of the stent or theintermediate portion to provide a clearance therebetween and facilitateresheathing for retraction of the stent and core assembly into thecatheter. Further, in some embodiments, the distal cover can bepositioned in the space radially between the catheter and the distal tipstructure of the core assembly. Thereafter, the catheter and/or coreassembly can be repositioned axially within the vasculature at a desiredlocation and the stent can be unsheathed, expanded, landed, and releasedinto the vasculature if the placement location is proper.

Therefore, in accordance with some embodiments, the distal cover canfacilitate resheathing of the core assembly. The resheathing of the coreassembly can be done with or without the stent engaged or secured withthe core assembly.

In some embodiments, the distal cover can also facilitate the retractionand withdrawal of the core assembly after the stent has been releasedinto the vasculature. As noted, the distal cover can be withdrawn intothe catheter in its second, unfurled, expanded, resheathing, or evertedposition or configuration. Whether or not the stent has been releasedinto the vasculature, the entire core assembly can be withdrawnproximally into the catheter and proximally removed from the catheter.Thus, if the stent has been released into the vasculature, the coreassembly can be removed from the catheter and a second core assembly canbe introduced into the catheter in order to deploy a second stent at thetreatment site. Such embodiments can provide significant advantages to aclinician including, for example, that the catheter need not bewithdrawn and removed from the vasculature in order to deploy a first orsubsequent stent to the treatment site. Accordingly then, thevasculature or need not undergo additional stress and the operation canbe performed with greater speed and efficiency.

The stent delivery system can also optionally include a steerable tipmechanism or steerable tip assembly. The steerable tip mechanism canallow a clinician to avoid abrading or perforating the vessel wallduring the procedure. In some embodiments, the steerable tip mechanismcan comprise a steerable wire having a curvilinear distal end. Forexample, a core member of the core assembly can be configured to besteerable by being rotatable relative to a protruding member (ifpresent) and the stent, the catheter, and/or other components of thestent delivery system. The core member can comprise a core wire.Further, the core wire can comprise a curved or arcuate distal sectionthat can be rotated or reoriented to point the core wire in a desireddirection by rotating the core wire. Accordingly, in some embodiments,the rotation of the core member relative to the stent can allow theclinician to avoid dislodging the stent from the vessel wall afterinitial expansion of the stent and also avoid abrasion or perforation ofthe blood vessel.

For example, in some embodiments, the stent can extend over a protrudingmember of the core member and be secured between the protruding memberand a constraining member. The protruding member can be rotatablycoupled to or supported on the core member such that the core member isrotatable relative to the stent, the protruding member, and theconstraining member. Accordingly, rotation of the core member can allowa clinician to adjust the position or orientation of a terminal ordistal portion of the core member. Further, in some embodiments, thedistal portion of the core member can be formed in an arcuate or curvedconfiguration to enable the core member to conform to tortuous vesselgeometries. For example, the distal portion of the core member cancomprise a curled, curved or arcuate tip that extends distally from thecore member and is oriented transverse to or bends away from a centralaxis of the catheter lumen.

Therefore, if the treatment site is adjacent to a tortuous vessellocation (e.g., a sharp turn in the vessel) or a bifurcation, forexample, the clinician can select or control the direction in which thecore member extends in order to avoid abrasions or perforations of thevessel during expansion and delivery of the stent at the treatment site.

For example, prior to or during unsheathing of the stent at thetreatment site, the clinician can observe the position of the distal tipassembly of the core member relative to surrounding vasculature. As thestent expands during the deployment process, it may generallyforeshorten, which can require or cause the core assembly including thedistal tip assembly to move distally to accommodate the shortening ofthe stent. This distal movement of the tip assembly can present anabrasion or perforation hazard, or a risk that the distal tip may engagethe vessel wall in a manner that can create an abrasion or perforationin the vessel. If the clinician can identify an abrasion or perforationhazard, the clinician can evaluate whether reorienting the tip wouldallow it to move distally without producing an abrasion or perforation.The clinician can use a proximal actuator of the stent delivery systemto rotate the core member, thereby rotating the distal tip of the coremember. In some embodiments, the distal tip can have a curvilinear orarcuate configuration. In some embodiments, the arcuate or curved partof the tip can be radiopaque to enable the physician to observe viafluoroscopy or other imaging the orientation of the tip relative to thesurrounding vasculature, and determine whether the tip should be rotatedor reoriented into a position wherein the further distal advance of thecore assembly is less likely to injure the vasculature. Such a positioncould be one wherein the tip points toward a lower-risk path (e.g., at abifurcation, the gentler rather than the sharper of the turns providedat the bifurcation, or the larger rather than the smaller vessel). Thus,rotation of the distal tip can reorient the direction of the core memberto avoid a bifurcation apex, a sharp turn in the vessel, or otherstructures of the vasculature which may represent an abrasion orperforation hazard. Thereafter, if the core member is distally advancedaxially within the vasculature, a properly oriented distal tip canfollow the path of the vasculature without abrading, perforating, orotherwise damaging the vessel wall.

Additionally, in some embodiments, the core assembly of the stentdelivery system can be configured to comprise one or more rotatableprotruding members mounted on the core member or core wire. Theprotruding member can be positioned axially adjacent to a distal end ofa constraining member extending over the core member. In someembodiments, the protruding member can have a cross-sectional outerprofile that is sized about equal to or greater than the cross-sectionalinner profile of the catheter. For example, the protruding member canhave a cross-sectional outer profile that is sized greater than theinner profile of the catheter.

Further, in some embodiments, the distal tip assembly or structure,e.g., including the distal cover, can be configured to rotate about thecore member. For example, an end of the distal cover can be rotatablycoupled with respect to the core member. Thus, the stent can beconfigured to rotate about the core member at least in part by virtue ofthe rotatable coupling of the distal cover.

As noted similarly above in other embodiments, a stent can extend overthe protruding member and be engaged or secured between the protrudingmember and the constraining member. The stent can have a variablediameter from a first portion to a second portion thereof as the stentis engaged in a frictional and/or interference fit. The rotatableprotruding member can allow the core assembly to exhibit torsionalflexibility which can reduce the pushing force required to move the coreassembly through the catheter the treatment site.

FIGS. 1-6 depict embodiments of a stent delivery system 100 which may beused to deliver and/or deploy a stent 200 into a hollow anatomicalstructure such as a blood vessel 102. The stent 200 can comprise aproximal end 202 and a distal end 204. The stent 200 can comprise abraided stent or other form of stent such as a laser-cut stent, roll-upstent etc. The stent 200 can optionally be configured to act as a “flowdiverter” device for treatment of aneurysms, such as those found inblood vessels including arteries in the brain or within the cranium, orin other locations in the body such as peripheral arteries. The stent200 can optionally be similar to any of the versions or sizes of thePIPELINE™ Embolization Device marketed by Covidien of Mansfield, Mass.USA. The stent 200 can further alternatively comprise any suitabletubular medical device and/or other features, as described herein.

As shown in FIG. 1, the depicted stent delivery system 100 can comprisean elongate tube or catheter 110 which slidably receives a core assembly140 configured to carry the stent 200 through the catheter 110. FIG. 2illustrates the core assembly 140 without depicting the catheter 110 forclarity. The depicted catheter 110 (see FIGS. 1, 5, 7, and 8) has aproximal end 112 and an opposing distal end 114, an internal lumen 116extending from the proximal end 112 to the distal end 114, and an innersurface 118 facing the lumen 116. At the distal end 114, the catheter110 has a distal opening 120 through which the core assembly 140 may beadvanced beyond the distal end 114 in order to expand the stent 200within the blood vessel 102. The proximal end 112 may include a catheterhub 122.

The catheter 110 can optionally comprise a microcatheter. For example,the catheter 110 can optionally comprise any of the various lengths ofthe MARKSMAN™ catheter available from Covidien of Mansfield, Mass. USA.The catheter 110 can optionally comprise a microcatheter having an innerdiameter of about 0.030 inches or less, and/or an outer diameter of 3French or less near the distal end 114. Instead of or in addition tothese specifications, the catheter 110 can comprise a microcatheterwhich is configured to percutaneously access the internal carotidartery, or a location within the neurovasculature distal of the internalcarotid artery, with its distal opening 120.

Information regarding additional embodiments of the catheter 110, andadditional details and components that can optionally be used orimplemented in the embodiments of the catheter described herein, can befound in U.S. Patent Application Publication No. US 2011/0238041 A1,published on Sep. 29, 2011, titled Variable Flexibility Catheter. Theentirety of the aforementioned publication is hereby incorporated byreference herein and made a part of this specification.

The core assembly 140 can comprise a core member 160 configured toextend generally longitudinally through the lumen 116 of the catheter110. The catheter 110 can define a generally longitudinal axis extendingbetween a proximal end and a distal end thereof. As discussed herein,the distal end of the catheter 110 can be positioned at a treatment sitewithin a patient. The core member 160 can comprise an intermediateportion 814 which is the portion of the core member onto or over whichthe stent 200 is positioned or extends when the core assembly 140 is inthe pre-deployment configuration as shown in FIGS. 1-5B, 13A and 13B.The stent 200 can be fitted onto or extend over the intermediate portionof the core member 160. The core member 160 can comprise a core wire.The core member 160 can have a proximal end or section 162 and aterminal or distal end 164. In some embodiments, the distal end 164and/or other portions of the core member 160 can be tapered such thatthe core member 164 becomes thinner as it extends distally.

The core member 160 can be coupled with, terminate at, or end in adistal tip. In some embodiments, the core member 160 can comprise aproximal section and a distal section. The distal section of the coremember 160 can be a distal tapering section, as illustrated. The distaltapering section can have a gradual taper that continues to the distaltip of the core member 160.

The distal tip of the core member 160 can comprise a distal portion orassembly 180. In some embodiments, the distal tip assembly 180 cancomprise a distal tip structure 182 and/or a distal cover 400 orstent-engaging portion. The distal tip structure 182 can comprise atleast one member or component that can be carried by the core member160. In some embodiments, the at least one member can be orientedgenerally transverse or parallel to the core member 160. For example,the tip structure 182 can comprise a coil(s), acircumferentially-extending band(s) of material, a clamp(s), and/orother structures that can pass smoothly within a vessel. Further, the atleast one member can comprise at least one segment of a coil or otherstructure.

In the illustrated embodiment, the core wire can optionally beconfigured to extend through the distal tip assembly 180 and terminateat the distal end 164. In some embodiments, the core member 160 can beconfigured to transmit torque and axial/longitudinal force from theproximal end 162 of the core member 160 to the distal end 164, where thedistal tip assembly 180 is disposed.

The distal end 164 of the core member 160 can be a flattened section ofthe core member 160. The distal end 164 can be flattened from a tapereddiameter of the core member 160 to a generally rectangular cross-sectionhaving a thickness sized less than the diameter of the adjacent portionof the core member. For example, the distal end 164 can have a thicknessof between about 0.0005 inches to about 0.003 inches. The distal end 164can thus be flattened from a distal portion of the core member 160having a diameter of between about 0.003 inches to about 0.005 inches.In some embodiments, the distal end 164 can be a flat portion having athickness of about 0.001 inches. Additionally, the length of the flatportion of the distal end 164 can be between about 8 mm and about 15 mm.In some embodiments, the length of the flat portion of the distal end164 can be between about 10 mm and about 12 mm. Whether in the form ofthe flattened wire described above, or of a distally extending tip coil,or other configuration, the distal end 164 can optionally be coveredwith or include radiopaque material, such as a radiopaque polymer. Onesuitable radiopaque polymer is a thermoplastic polyurethane (e.g.,PELLETHANE™ 80A or TECOFLEX™) doped with a radiopacifier such astungsten or barium sulfate.

As illustrated in FIGS. 1-2, some embodiments of the core member 160 canbe configured with an arcuate or curved distal end 164. The distal end164 extends distally from the core member 160 and can be orientedtransverse to or bend away from a central axis of the catheter lumen116. The distal end 164 can be curved or bent to form an angle ofapproximately 45 degrees with the longitudinal axis of the core member160. The distal end 164 can be heat-set or otherwise processed to retainthe arcuate/curved/angled configuration. As discussed further herein,the core member 160 can be twisted or torqued to rotate the arcuate orcurved distal end 164 thereof in order to advantageously allow aclinician to carefully navigate and steer the distal tip assembly 180and core member 160 through tortuous vessel geometry, thereby avoidingabrasion or perforation of a vessel wall.

The distal tip assembly 180 may be coupled axially adjacent to thedistal end 164 of the core member 160. Moreover, the core member 160 mayextend into and form a core of the distal tip assembly 180, or otherwisebe connected to the distal tip assembly 180.

In some embodiments, the distal tip assembly 180 can be rotatablycoupled to the distal end 164 of the core member 160. As discussedfurther herein, a rotatable coupling between the distal end 164 of thecore member 160 and the distal tip assembly 180 can allow the coremember 160 to rotate independently relative to the distal tip assembly180 (and possibly other components of the core assembly 140). Suchrelative rotation can advantageously impart greater flexibility to thecore assembly 140 as it is passed through the catheter 110 to thetreatment site. Further, in embodiments in which the distal end 164 ofthe core member 160 extends distally beyond the distal tip assembly 180,such relative rotation can also advantageously allow the distal end 164to be rotated independently of the distal tip assembly 180, which mayreduce any torsional stress on the stent 200, the core assembly 140,and/or the surrounding vasculature.

However, in other embodiments, the distal tip assembly 180 can berigidly or fixedly coupled to the distal end 164 of the core member 160such that the distal tip assembly 180 and the core member 160 rotate asa single unit. For example, the core member 160 can be operativelycoupled with the distal tip assembly 180 such that the distal tipassembly 180 is usable to radially direct or steer the core member 160within the catheter 110 and/or a blood vessel by twisting or torquingthe core member 160.

The distal tip structure 182 can be configured to comprise an atraumaticdistal end face formed by a rounded solder bead, especially inembodiments in which the distal end 164 of the core member 160 does notextend distally beyond the distal tip assembly 180. Further, the distaltip structure 182 can have other atraumatic shapes designed to avoidinjury to the vessel into which it may be introduced.

The core member 160 can be sufficiently flexible to allow flexure andbend as it traverses tortuous blood vessels. In some embodiments, thecore member 160 can be tapered along at least part of its length orcontain multiple tapering or stepped sections of different diameters orprofiles, and become narrower and more flexible as it extends distally.

The core assembly 140 may also optionally include a proximal retainingmember 220 located proximal of the stent 200. The proximal retainingmember 220 can comprise one or more materials. For example, in someembodiments, the proximal retaining member 220 may include a marker band222 fixed to the core member 160 via a solder bead 224 or other suitableconnection. The marker band 222 may be a generally cylindrical structuremade of platinum or other radiopaque material. In at least oneembodiment, the proximal retaining member 220 may be arranged in thecore assembly 140 such that there is a small gap, e.g., from about 0.0mm to about 0.5 mm, axially between the band 222 of the retaining member220 and the proximal end 202 of the stent 200.

In embodiments where the marker band 222 of the proximal retainingmember 220 is made of platinum or another radiopaque material/substancevisible through fluoroscopy, CAT scan, X-Ray, MRI, ultrasound technologyor other imaging, a user may be able to determine the location and trackthe progress of the proximal end 202 of the stent 200 within thecatheter 110 or blood vessel 102 by determining the location of theproximal retaining member 220.

Instead of, or in addition to, the depicted components of the proximalretaining member 220, the retaining member 220 may include a marker coil(not shown) or a coil or other sleeve (not shown) having alongitudinally oriented, distally open lumen that at least partiallyreceives and surrounds the proximal end 202 and/or other proximalportion of the stent 200. Further, the proximal retaining member 220 canalso comprise a biasing member, such as a coil spring wound around thecore member 160, which can be configured to bias the stent 200 in thedistal direction.

Referring now to FIG. 3A, some embodiments of the system 100 can alsocomprise a stent holding assembly 300 configured to releasably engage aproximal portion 206 of the stent 200. The stent holding assembly 300can enable a clinician to secure, grasp, or engage the proximal portion206 of the stent 200 in a manner that allows the stent to be controlled,positioned, and released at a precise, desired position within thevessel. In some embodiments, the stent holding assembly 300 can enable aclinician to push the stent distally, pull the stent proximally,unsheath or move the stent distally beyond the distal end of thecatheter, and/or recapture, collapse, withdraw, or resheath the stentinto the catheter after the stent has been partially expanded within thevessel.

Further, in accordance with some embodiments, the stent holding assembly300 can be configured to accomplish such superior control using only thesecurement, grasping, or engagement between the stent holding assembly300 and the proximal portion 206 of the stent 200. Thus, a distalportion 210 of the stent need not undergo or directly receive thepushing or pulling forces exerted by the clinician. Instead, the distalportion 210 of the stent can be guided by the forces exerted on theproximal portion of the stent and generally expand freely when movedoutside of the catheter. As such, the clinician can carefully controlthe axial position of the distal portion of the stent in order toproperly land the stent within the vessel and should the stent need tobe repositioned, the clinician can recapture, collapse, withdraw, orresheath the stent into the catheter and attempt to land the stent againwithin the vessel at the desired position.

The stent holding assembly can comprise one or more components thatcooperate to secure, grasp, or engage a portion of the stent 200. Insome embodiments, a component attached to, coupled to, carried by, orformed on the core member 160 can cooperate with other structures of thesystem 100 in order to provide such superior stent control.

For example, as seen in FIGS. 2-3A, the core assembly 140 can alsocomprise a constraining member or outer grip member 320. Theconstraining member 320 can have a proximal end 322 and a distal end324. The constraining member 320 can comprise an elongate sheath havinga central lumen extending between the proximal end 322 and the distalend 324. The central lumen can be configured to receive the core member160 therethrough.

In some embodiments, the constraining member can be a simple tube orsheath. For example, the constraining member can have an inner diameterof between about 0.015 inches and about 0.023 inches. The inner diametercan also be between about 0.017 inches and about 0.021 inches. In someembodiments, the inner diameter can be about 0.017 inches or about 0.021inches. Further, an outer diameter of the constraining member can bebetween about 0.018 inches and about 0.028 inches. The outer diametercan also be between about 0.020 inches and about 0.026 inches. In someembodiments, the outer diameter can be about 0.020 inches or about 0.025inches. The axial length of the constraining member can also be betweenabout 150 cm and about 200 cm. Further, the constraining member can beformed from a flexible material. For example, the constraining membercan be formed from material such as PTFE, polyimide, or other suchpolymers.

However, the constraining member can also be configured as a structuralalternative to a simple tube or sheath. Such structures can include adistal end portion that is “fully” tubular coupled to a proximal portionthat is made up of one or more longitudinal struts or wires, or thatcomprises a slotted or spiral-cut tube. In any of the disclosedconstraining members, the distal end portion may comprise a coil (e.g.,a metallic coil) or other form of proximally retractable sleeve suitablysized for use in the core assembly 140.

Further, the core assembly 140 can also comprise at least one stopmember. The stop member can comprise a protrusion or a recess disposedalong the core member 160. For example, the stop member can comprise aprotruding member or inner grip member 340. The protruding or inner gripmember 340 can be a radially extending component. The protruding orinner grip member 340 can be disposed along the core member 160 betweenthe distal section 164 and the proximal section 162 thereof. Forexample, the protruding member 340 can be disposed axially between theproximal section 162 and the distal section of the core member 160. Inaccordance with some embodiments, the stent holding assembly 300 can beconfigured such that the constraining member 320 and the protrudingmember 340 cooperate to secure, engage, or grip the proximal end 202and/or proximal portion 206 of the stent 200. Further, the constrainingmember 320 can be longitudinally displaceable relative to the coremember 160 and/or the protruding member 340 to release the proximalportion of the stent and allow it to expand within the vessel. Thus,during axial advancement or withdrawal of the stent 200 within the lumen116 of the catheter 110 or expansion of the stent 200 within the vessel,the proximal portion 206 of the stent 200 can be controlled by the stentholding assembly 300.

In some embodiments, the stent holding assembly 300 can be configuredsuch that one or more components thereof define a capture area in whichat least a portion of the proximal portion of the stent can be secured,engaged, or grasped. The capture area can extend around at least aportion of the circumference of the core member 160. Accordingly, atleast a portion of the circumference of the proximal portion of thestent can be secured, engaged, or grasped in the capture area.

As shown in FIG. 3A, the depicted embodiment illustrates that theconstraining member 320 can comprise a tube or sheath that receives aportion of the core member 160 in a lumen of the constraining member320. The distal end 324 of the constraining member 320 can be spacedapart from the core member 160 to define a capture area 350therebetween. The capture area 350 in the illustrated embodiment can beformed as a generally cylindrically shaped gap configured to receive atleast the proximal end 202 of the stent 200 therewithin. Accordingly,the distal end 324 of the constraining member 320 can circumferentiallyat least partially cover or surround at least the proximal end 202 ofthe stent 200 when the proximal end 202 is received axially within thecapture area 350.

In some embodiments, a distal portion of the constraining member can befitted over or extend over the proximal end of the stent. As shown inFIGS. 1-3A, proximal end 202 of the stent 200 can be positioned in thelumen of the constraining member 320; preferably the proximal endportion of the stent 200 is slightly radially compressed and liesradially adjacent to the inner wall of the constraining member 320. Theprotruding member 340 can hold the proximal portion of the stent 200 inthe constraining member 320. Where the protruding member 340 is locateddistal of the distal end of the constraining member 320, this can beaccomplished in whole or in part by engaging, securing, or gripping thestent 200 between the protruding member 340 and the rim of the distalopening of the constraining member 320. In such embodiments, the stent200 can be engaged, secured, or gripped in a generally axial direction.Where the protruding member 340 is positioned partly or wholly withinthe lumen of the constraining member 320, this can be accomplished inwhole or in part by gripping the stent 200 between the outer surface ofthe protruding member 340 and the inner surface of the constrainingmember 320. In such embodiments, the stent 200 can be engaged, secured,or gripped in a generally radial direction. Further, some embodimentscan be provided in which the stent 200 can be engaged, secured, orgripped in a direction transverse to the radial and axial directions.

In certain embodiments, the outer surface of the protruding member 340can be tapered such that its outer diameter increases in a distaldirection, and the inner surface of the constraining member 320 may betapered to match the taper of the protruding member 340. In thoseembodiments, the stent 200 may be gripped between the outer surface ofthe protruding member 340 and the inner surface of the constrainingmember 320, and/or between the protruding member 340 and the rim of thedistal opening of the constraining member 320.

With reference to FIGS. 1-4B and 7-10, preferably only a relativelysmall portion (e.g., significantly less than half the length, or lessthan 25% of the length, or less than 10% of the length) of the stent 200is positioned axially within the constraining member 320. In thedelivery or in-catheter configuration shown in FIG. 1, the balance ofthe stent 200 extends distally and somewhat radially outward of thedistal end 324 of the constraining member 320, preferably lying radiallyadjacent the inner surface 118 of the catheter 110 except where thedistal portion 210 of the stent extends into a distal cover or distalstent covering 400 (discussed further herein). For example, the axiallength of the constraining member that extends over the stent can bebetween about 4 mm and 15 mm. The axial length of the constrainingmember that extends over the stent can also be between about 6 mm and 10mm. Further, in some embodiments, the axial length of the constrainingmember that extends over the stent can be about 8 mm.

Further, in the embodiment of FIG. 3A, the retaining member 220 is shownin dashed lines to illustrate that this component can optionally beincluded in some embodiments of the stent holding assembly 300. Thesecurement, gripping, or engagement of the proximal portion 206 of thestent 200 can be accomplished with or without the use of the retainingmember 220. However, in some embodiments, the retaining member 220 canprovide a proximal limit to stent migration and tend to ensure that thestent 200 does not migrate proximally as the constraining member 320 ismoved proximally relative to the protruding member 340 when the stent200 is being released. The retaining member 220 can be formed integrallywith the core member 160, such as being formed from a single, continuouspiece of material. However, the retaining member 220 can also be formedseparately from and later coupled to the core member 160. In someembodiments, the retaining member 220 can be fixed relative to the coremember 160. However, the retaining member 220 can also be free to rotateand/or slide longitudinally along the core member 160.

In accordance with some embodiments, the stop or protruding member 340can extend in a radial direction about at least a portion of thecircumference of the core member. The protruding member can have anouter surface that extends radially beyond or is spaced radially apartfrom an outer surface of the core member. The protruding member can begenerally cylindrically shaped, oval shaped, or annularly shaped. Theprotruding member can be an annular ring, a cylindrical sleeve, or othersuch structure. However, the protruding member can also have one or moreradially extending protuberances that do not extend about the entirecircumference of the core member. The protruding member can also beconfigured to extend along at least a portion of the axial length of theintermediate portion of the core member.

The stop or protruding member can be formed from a material that can beshrink-fitted onto the core member. The stop or protruding member canalso be configured to comprise one or more materials. For example, insome embodiments, the protruding member can formed from a materialhaving 30% BaSO4. The protruding member can define an axial length ofbetween about 1 mm and about 5 mm. In some embodiments, the protrudingmember can define an axial length of between about 2 mm and about 4 mm.Further, in some embodiments, the protruding member can define an axiallength of about 2 mm. The protruding member can define an inner diameterof between about 0.005 inches and about 0.015 inches. The inner diametercan also be between about 0.009 inches and about 0.013 inches. In someembodiments, the inner diameter can be about 0.006 inches, about 0.007inches, or about 0.011 inches. Furthermore, in some embodiments, theprotruding member can define an outer diameter of between about 0.013inches and about 0.030 inches. The outer diameter can also be betweenabout 0.019 inches and about 0.025 inches. In some embodiments, theouter diameter can be about 0.014 inches or about 0.020 inches.

The protruding member can be formed integrally with the core member as asingle, continuous piece of material. For example, the protruding membercan be an enlarged portion of the core member having a diameter orprofile that is sized greater than a diameter or profile of the axiallyadjacent portions of the core member. However, the protruding member canalso be formed separately from the core member and coupled thereto. Forexample, in some embodiments discussed further herein, the protrudingmember can be rotatably coupled to the core member. Alternatively, theprotruding member can also be fixedly coupled to the core member.

Further, one or more protruding members can be used in some embodiments.For example, as shown in FIG. 6, the core assembly 840 is illustratedwith a first protruding member 844 and a second protruding member 846positioned along a core member 860. The first and second protrudingmembers 844, 846 can be configured or operate in accordance with theconfigurations and functions discussed herein with respect to any of theembodiments of the protruding members. Further, the first and secondprotruding members 844, 846 can be configured to slide relative to eachother or otherwise cooperate to support the stent on the core assembly840.

With reference again to FIG. 3A, the protruding member 340 is shown as aradially prominent component that is integrally formed with the coremember 160 from a continuous piece of material. The protruding member340 is a generally cylindrically shaped component having a proximalsection 342. The proximal section 342 can comprise a proximal wallextending in a radial direction upwardly from the core member 160, anouter circumferential surface extending generally parallel relative to alongitudinal axis of the core member 160, and/or an edge formed betweenthe proximal wall and the outer circumferential surface. The edge can berounded or be formed having a generally perpendicular orientation.

The protruding member 340 can alternatively comprise a component that isseparate from the core member 160 (see, e.g., FIG. 1). Such a protrudingmember can comprise, for example, a tube of polymer or other suitablematerial that is attached to the core member 160 via adhesives, heatshrinking, or any other suitable technique. In one embodiment, theprotruding member 340 comprises a polymeric tube which surrounds thecore member 160, which passes through a lumen of the tube. One or morecoils of metallic wire (such as platinum or platinum-alloy wire, notshown) can be wrapped around and welded to the core member 160, andthereby interposed between the core member and the polymeric tube toserve as a mechanical interlock therebetween. Preferably, the tube isheat shrink material such as PET that is heat-shrunk onto the outersurface of the coil(s), so that the shrunken tube adheres closely to thecoil(s) and becomes securely attached to the core member 160. Aprotruding member 340 that can rotate about, and/or move longitudinallyalong, the core member 160 can be constructed in a somewhat similarmanner. In this case, the underlying coil(s) can have a luminal insidediameter that is slightly larger than the outside diameter of the coremember 160. The desired coil luminal inside diameter can be set bywinding the coil(s) on an appropriately sized mandrel. The polymerictube is then heat-shrunk onto the coil(s) (or otherwise joined thereto)to form the outer portion of the protruding member 340. The resultingprotruding member 340 is then slid over the core member 160 to itsdesired position thereon, where the protruding member can rotate and/ortranslate with respect to the core member. Stop(s) can be formed on thecore member 160 proximal and/or distal of the rotatable/translatableprotruding member 340, to set boundaries for any longitudinal movementof the protruding member and allow it to rotate. Such stop(s) can beformed in the manner described above for the fixed protruding member,with an underlying coil welded to the core member and an overlyingshrink tube, but at a somewhat smaller outside diameter than theprotruding member.

As illustrated in FIG. 3A, the proximal portion 206 of the stent 200 canextend over the protruding member 340 and the proximal end 202 of thestent can extend into the capture area 350 formed radially between theconstraining member 320 and the core member 160. In this embodiment,these components cooperate to form the stent holding assembly 300, whichcan secure, engage, or grip the proximal end 202 and/or proximal portion206 of the stent 200. Thus, during axial advancement or withdrawal ofthe stent 200 within the lumen 116 of the catheter 110 or duringexpansion of the stent 200 within the vessel, the proximal portion 206of the stent 200 can be controlled by the stent holding assembly 300.

In particular, the protruding member 340 and the constraining member 320can cooperate to engage, secure, or grasp the stent 200 in a press fit,an interference fit, or a frictional fit, as illustrated in FIGS. 3A-4B.The presence of the protruding member 340 can create a slight increasein the diameter of the stent 200 axially adjacent to the distal end 324of the constraining member 320. Thus, the diameter of the proximal end202 of the stent 200 within the capture area 350 can become smaller thanthe diameter of the stent 200 extending over the protruding member 340.Instead of or in addition to these conditions, the stent 200 can be infrictional contact with a distal inner surface 331 and/or edge 332 ofthe sidewall of the constraining member 320 and the proximal section 342of the protruding member 340, thereby securing, engaging, or graspingthe stent 200 therebetween.

Further, in some embodiments, the protruding member 340 can have anouter profile or diameter that is sized about equal to or greater thanan inner profile or inner diameter of the lumen of the constrainingmember 320. The relative sizing of the profiles of the protruding member340 and the constraining member 320 can be configured such that theprotruding member 340 can be positioned axially adjacent to theconstraining member 320 in order to “pinch,” secure, grasp, or engagethe proximal portion 206 of the stent 200 in a press or interferencefit. The outer profile of the protruding member 340 can also beconfigured to be sized less than the inner profile of the lumen of theconstraining member 320 if the stent thickness is sufficient to createan interference or otherwise restrict or slow movement of the protrudingmember 340 into or through the lumen of the constraining member 320. Forexample, a collective outer profile of the stent 200 and the protrudingmember 340 can be sized greater than the inner profile of the lumen ofthe constraining member 320. In some embodiments, the collective outerprofile can be an outside diameter measured by adding the outsidediameter of the protruding member 340 and two times the thickness of thestent 200. However, in other embodiments the outer and inner profiles(which can be measured as a size or shape of a cross section of thecorresponding component(s)) can be noncircular, comprise one or moreradial protrusions, or otherwise comprise shapes that are other thancircular or rounded.

Additionally, although the embodiment illustrated in FIG. 3A illustratesthat the stent 200 can be secured, grasped, or engaged without havingthe protruding member 340 enter the lumen of the constraining member320, in some embodiments the protruding member 340 extends into or isreceived at least partially in the lumen of the constraining member 320.

FIG. 3B illustrates an alternative embodiment of an stent holdingassembly. As noted herein, the configuration of the core member, stopmember, and retaining member can be varied in accordance with severalembodiments. FIG. 3B illustrates a stent holding assembly 300′ in whicha stop member is formed as a recess 170 within a body of a core member160′. The recess 170 can extend circumferentially around the core member160′ to provide a capture area 350′ configured to receive at least aportion of the proximal end 202′ of the stent 200′. Alternatively, therecess 170 can comprise one or more indentations into which a portion ofthe proximal portion 206′ of the stent 200′ can be received.

Thus, in the illustrated embodiment of FIG. 3B, the core member 160′ canhave a generally constant diameter (or a tapering diameter) and therecess 170 can be configured to receive at least a portion of a proximalportion of the stent 200′. The diameter of the core member 160′ can besized larger along a protruding member section 340′ than along aproximal section that extends within a lumen of a constraining member320′. However, the relative diameters of the sections of the core member160′ can be varied and configured in relation to the inner diameter orinner profile of the constraining member 320′, as discussed similarlyabove with respect to FIG. 3A. As with the embodiments discussed above,the stent holding assembly 300′ can cooperatively engage, secure, orgrasp a proximal portion 206′ of the stent 200′ in order to providesuperior control of the stent 200′ during the operation.

Referring again to FIG. 2, embodiments of the system 100 can beconfigured such that the constraining member 320 can be removablycoupled relative to the core member 160 via a removable, disengageableor breakable coupling 360 (or otherwise selectively longitudinallymoveable, adjustable or retractable relative to the core member 160).The coupling 360 is located preferably near the proximal end 162 of thecore member 160, or at another location on the core member that isaccessible to the clinician outside of the patient's body, proximal ofthe hub 122 or other proximal end portion of the catheter 110. Theconstraining member 320 can extend distally from a proximal end 322thereof at the coupling 360 to a distal end 324 that is located slightlyproximal of (or overlying) the protruding member 340.

A longitudinal or axial position of the constraining member 320 relativeto the core member 160 can be maintained or modified by means of thecoupling 360. The coupling 360 can be located at a proximal locationthat is outside of a body lumen such that a clinician can actuate thecoupling 360 to either maintain or change the relative axial positioningof the constraining member 320 relative to the core member 160.Accordingly, in some embodiments, a clinician can disengage or break abond between the coupling 360 and the constraining member 320 in orderto move the distal end 324 of the constraining member 320 relative tothe core member 160. The clinician can therefore maintain an engagement,securement, or grasp of the stent using the stent holding assembly untilthe stent is positioned at a desired location at the treatment site.Once the stent is in the desired location and properly landed, theclinician can thereafter disengage and release the stent by actuatingthe coupling 360 to proximally withdraw the constraining member 320relative to the core member 160 (or to enable the subsequent proximalwithdrawal of the constraining member).

Further, in some embodiments, the coupling 360 and the constrainingmember 320 can be configured with one or more stop points along a rangeof longitudinal movement of the constraining member 320 relative to thecore member 160. Such stop points can control the relative axialmovement between the constraining member 320 and the core member 160,causing the constraining member to stop at one or more desiredlocations. For example, a first stop point can be provided wherein theconstraining member 320 is in an engaged position (e.g., wherein theproximal portion of the stent is gripped by the stent holding assembly300). The first stop point may indicate tactily to the clinician thatthe constraining member 320 is positioned to grip the proximal portionof the stent. Instead of or in addition to the first stop point, asecond stop point can be provided that tactily signals to the clinicianthat the constraining member 320 has been proximally retracted relativeto the core member 160 and/or stop member by a distance that issufficient to ensure that the stent has been be released from the stentholding assembly.

The embodiments disclosed herein provide useful advantages. In additionto those discussed herein, the stent holding assembly can provide asystem with superior flexibility and therefore lower the delivery forcenecessary to advance the system to the treatment site. To some extent,the stent holding assembly retains a portion of the stent in a collapsedconfiguration which will tend to lessen the amount of frictionalengagement between the stent and the inner surface of the catheter,further decreasing the delivery force required.

Moreover, as discussed further herein, some embodiments can provide fora delivery system in which the distal end of the stent automaticallyexpands upon exiting the distal end of the catheter, thereby eliminatingthe need for structure that controls the expansion characteristics ofthe distal end of the stent. For example, some embodiments disclosedherein would not require a distal cover that would have to be rotated orotherwise moved to disengage from the distal end of the stent.

Furthermore, embodiments of the stent holding structure can enable aclinician to recapture, collapse, withdraw, or resheath the stent towithin the catheter after partial expansion of the stent. Even insituations where the entire stent has exited the catheter lumen, someembodiments of the stent holding structure disclosed herein can enablethe clinician to recapture, collapse, withdraw, or resheath the proximalportion of the stent and therefore the entire stent into the catheterlumen so that the core assembly can be entirely withdrawn or to allowthe stent to be repositioned and landed again at a desired location atthe treatment site.

As noted above, the stop member or protruding member of the coreassembly can be formed integrally with the core member as a single,continuous piece of material or formed separately from the core memberand coupled thereto. In some embodiments, the protruding member can berotatably coupled to the core member.

For example, referring to FIGS. 4A-B, alternative embodiments of thestop member or protruding member are shown. As shown in FIG. 4A,similarly to FIG. 3A, core assembly 600 comprises a constraining member620, a distal cover 630, a protruding member 640, a core member 660, anda stent 670. The protruding member 640 can be formed from a single,continuous piece of material with the core member 660, as discussedabove with respect to some embodiments.

However, FIG. 4B illustrates another core assembly 700 that comprises aconstraining member 720, a distal cover 730, a protruding member 740,and a core member 760. The protruding member 740 is formed separatelyfrom the core member 760. The protruding member 740 can optionally beconfigured to rotate with respect to the core member 760. Accordingly,in the core assembly 700, the core member 760 can rotate freely withinthe constraining member 720, the protruding member 740, and the stent770. In some such embodiments, a distal tip assembly 780 of the coreassembly 700 can be rotatably coupled relative to the core member 760,which can allow the core member 760 to also rotate freely relative tothe distal tip assembly 780 instead of or in addition to the protrudingmember 740 and stent 770.

In embodiments using a rotatable stop member or protruding member, thecore assembly can exhibit improved flexibility and also reduce torsionalstress on the stent mounted thereon. Accordingly, while the coreassembly is being delivered to the treatment site, the rotationalfreedom of the core member can allow the core member to adjust as ittraverses tortuous pathways without transferring a torque to the stent.This enhanced rotatability can reduce “whipping.” Further, the improvedflexibility of the core assembly can also reduce the required deliveryforce.

Additionally, in some embodiments, the rotatable stop member orprotruding member can be rotatably coupled relative to the core memberwhile the distal tip assembly is fixedly coupled relative to the coremember such that the distal tip assembly and the core member rotate as aunit. In such embodiments, the rotatability of the protruding member canbe indirectly affected via the contact of the stent with the distal tipassembly and the protruding member. Although the stent may not berotatably fixed relative to the distal tip assembly, the interactionbetween the distal tip assembly and the stent may create some resistanceto rotation of the stent relative to the core member that wouldotherwise be freely permitted at the interconnection of the protrudingmember and the core member. However, once the distal tip assembly exitsthe catheter and the distal end of the stent is allowed to expand, thecore member can freely rotate relative to the protruding member and thestent.

In accordance with aspects of some embodiments, the stop or protrudingmember can also be configured to slide longitudinally relative to thecore member, instead of or in addition to any rotational capability. Forexample, the stop or protruding member and the core member can beconfigured such that the core member comprises one or more protrusionsor limits against which the stop or protruding member can abut to limitthe longitudinal movement (proximal or distal) of the stop or protrudingmember.

The protruding member preferably comprises a relatively soft orcompressible cylindrical member, and can be formed from a suitablepolymer or elastomer. In some embodiments, the outside diameter of theprotruding member is preferably sufficiently small relative to theinside diameter of the catheter to inhibit the protruding member fromgripping or urging the stent against the inner wall of the catheter andthereby generating significant friction between the stent and catheter.For example, as illustrated in FIG. 1, the protruding member 340 canleave sufficient radial space between the outer surface of theprotruding member 340 and an inner surface or wall 118 of the catheter110 to allow the stent wall to move radially between the protrudingmember 340 and catheter inner surface 118 when otherwise unconstrained.Alternatively, the protruding member 340 may be sized and configured togrip the stent 200 against the inner surface 118 of the catheter 110.

In the depicted core assembly 140, the constraining member 320 and theprotruding member 340 can grip the stent 200 to facilitate delivery ofthe stent 200 through the lumen 116 of the catheter 110, and resheathingof the stent 200 when partially expanded, while completely orsubstantially isolating the catheter 110 from the grip forces involvedin gripping the stent 200 by the core assembly 140. In this manner, thecore assembly 140 may securely grip the proximal end of the stent200—securely enough even to facilitate resheathing—without generatinghigh radial friction forces between the stent 200 and the inner surface118 of the catheter 110 that can impede advancement of the stent throughthe catheter 110. Instead, only relatively light radial frictionalforces may exist between the stent 200 and the catheter 110, generatedby the stent self-expanding against the inner surface 118, that do notsignificantly impede axial advancement of the stent 200 within the lumen116 of the catheter 110.

It may also be observed that the stent delivery system 100 can grip thestent 200 radially and/or axially between components that do not (orneed not) move with respect to each other during axial movement of thestent within the lumen 116 of the catheter 110, thereby reducing thefriction that may arise between two components (the core assembly 140and the catheter 110) that can move with respect to each other by asignificant distance during delivery of the stent 200. The catheter 110may remain relatively stationary within the patient's vasculature whilethe core assembly 140 and stent 200 are advanced to and/or through thedistal end of the catheter 110. During this advancement, theconstraining member 320 and the protruding member 340 may remainstationary with respect to each other, and either one or both remainstationary with respect to the stent 200.

Structures other than the herein-described embodiments of theconstraining member 320 and the protruding member 340 may be used in thecore assembly 140 to move the stent 200 along the catheter 110. Forexample, the constraining member 320 and the protruding member 340 maybe omitted and the proximal bumper 220 employed for that purpose.Instead of, or in addition to, the bumper 220, additional pads orbumpers may be mounted on the core member 160, underlying the stent 200and configured to cooperate with the radially adjacent portions of thecatheter sidewall to grip the stent 200 and facilitate movement alongthe catheter 110.

In accordance with some embodiments, the distal tip assembly of the coreassembly can comprise a distal cover configured to reduce frictionbetween the stent (e.g., the distal portion or distal end thereof) andthe inner surface of the catheter. The distal tip assembly can beconfigured to comprise either or both the distal tip structure and thedistal cover.

Some embodiments can be provided in which the distal cover provides arestrictive force that aids in maintaining the distal portion of thestent in a collapsed configuration until released by the clinician.However, the distal cover of other embodiments disclosed herein does noton its own provide a restraining force to maintain the stent in acollapsed diameter.

For example, the distal cover can be configured as a lubricious,flexible structure having a free first end or section that can extendover at least a portion of the stent and/or intermediate portion of thecore assembly and a fixed second end or section that can be coupled tothe distal tip structure and/or the core member at an attachment point.The second section may be coupled directly to the core member orindirectly to the core member, for example by being coupled to thedistal tip structure. The distal cover can have a first or deliveryposition, configuration, or orientation (see, e.g., FIGS. 1, 2, 4A, 4B,5A, 5B, 6, 13A, 13B) in which the distal cover can extend proximallyrelative to the distal tip structure or the attachment point and atleast partially surround or cover a distal portion of the stent.Further, the distal cover can be movable from the first or deliveryorientation to a second or resheathing position, configuration, ororientation (see, e.g., FIGS. 7B-7C, 8-12) in which the distal cover canbe everted such that the first end of the distal cover is positioneddistally relative to the second end of the distal cover to enable theresheathing of the core assembly 140, either with the stent 200 held bythe stent holding assembly 300, or without the stent.

FIGS. 5A and 5B depict embodiments of the distal cover 400. Theembodiments of FIGS. 5A and 5B can be similar to each other instructure, function and method of use, except for the manner in whichthe cover 400 is attached to the core assembly 140. Accordingly, in thediscussion herein of the distal cover 400/400′, any mention of acomponent having a reference numeral used in FIG. 5A (e.g. 420) shouldbe understood to include the corresponding “prime” reference numeralused in FIG. 5B (e.g. 420′), and to apply with equal force to thecomponent so designated in FIG. 5B, and vice versa.

Referring to FIGS. 5A-5B, the core assembly 140 may include the distalcover 400 which, as noted above, can be configured to reduce radialfriction between the stent 200 (e.g., the distal portion 210 or distalend 204 thereof) and the inner surface 118 of the catheter 110. Thedistal cover 400 may include a free first section or end 420 and a fixedsecond section or end 440. As illustrated, the second section 440 iscoupled indirectly to the core member 160 via the distal tip structure182, which is discussed further below.

Further, as shown in FIGS. 5A-5B, at least a portion of the distal cover400 can at least partially extend or be interposed radially between thedistal portion 210 of the stent 200 and the inner surface 118 of thecatheter 110 in the first position, configuration, or orientation. Inthe first orientation, the first section 420 of the distal cover 400 canextend from the second section 440 in a proximal direction to a pointwhere the first section is interposed between the distal portion 210 ofthe stent 200 and the inner surface 118 of the catheter 110. In thisorientation, the first section of the distal cover can take on a“proximally oriented” position or configuration.

The core assembly 140 shown in FIGS. 5A-5B can operate as illustrated inFIGS. 7A-C. Referring to FIGS. 7A-C, the core assembly 140 can bedistally advanced until the distal portion 210 of the stent 200 ispositioned distally beyond the distal end 114 of the catheter 110 topermit expansion of the distal portion 210 of the stent 200 into a lumen104 of the blood vessel 102. As the distal portion 210 of the stent 200expands, it can cause the distal cover 400 to be opened or moved fromthe first orientation. Because the stent 200 can foreshorten as itexpands, the stent 200 can withdraw from engagement with the distalcover 400, as shown in FIG. 7A.

After the distal cover 400 has become disengaged from the stent 200 toreach the state shown in FIG. 7A, the cover can proceed to the secondorientation as shown in FIG. 7B or 7C, as oncoming blood flow urges thefirst section 420 distally. Alternatively, the distal cover 400 canremain substantially in the disengaged, distally-extending configurationshown in FIG. 7A until the core assembly 140 is withdrawn proximallyinto the catheter 110, at which point the distal end of the catheter 110can force the approaching first section 420 of the cover 400 to evert orotherwise take on the second configuration as shown in FIG. 10 or 12. Ineach case, the distal cover 400 can move toward an everted position orconfiguration in which the first section 420 of the distal cover 400 isflipped, everted or rotated to extend in a distal direction or in a“distally oriented” position or configuration. In some embodiments of adistally-oriented second configuration, all or at least a portion of thefirst section 420 is located distal of all or at least a portion of thesecond section 440.

The stent 200 can be further unsheathed (as shown in FIG. 8) andsubsequently released (as shown in FIG. 11), or the stent 200 can beretracted and withdrawn back into the catheter 110 (as shown in FIGS.9-10), if needed. In either situation, when the distal portion of thecore assembly 140 is withdrawn into the lumen of the catheter 110, thedistal cover 400 can be retracted into the catheter 110 in the secondposition, configuration, or orientation, in which the distal cover 400can be at least partially everted, as shown in FIGS. 9-10 and 12. Thiscan facilitate complete resheathing of the stent 200 and/or the coreassembly 140 within the catheter 110.

In some embodiments, in the first orientation, the first section 420 ofthe distal cover 400 is positioned outside of a radial space 800 locatedbetween the tip assembly 180 and the catheter 110, as shown in FIG. 5.The distal cover 400 can extend proximally from the distal portion orthe tip assembly 180 and from the radial space 800 between the distalportion or tip assembly 180 and the catheter 110. Additionally, in somesuch embodiments, in the second orientation, the first section 420 ofthe distal cover 400 extends distally through the radial space 800 uponretraction of the core assembly 140 into the catheter 110, as shown inFIGS. 10 and 12.

Further, in some embodiments, in the first orientation, at least aportion of the distal cover 400 can extend into a radial space 804within the catheter lumen 116 located between a distal end 812 of theintermediate portion 814 of the core member 160 and the distal end 114of the catheter 110. For example, referring to FIGS. 5A-B, the firstsection 420 of the distal cover 400 can extend or be interposed radiallybetween the distal end 812 of the intermediate portion 814 and the innersurface 118 of the catheter 110. Additionally, in some embodiments, inthe second orientation, the first section 420 of the distal cover 400 nolonger extends or is no longer interposed radially between the distalend 812 of the intermediate portion 814 and the inner surface 118 of thecatheter 110 (and the first section 420 can be located distally of suchlocation), upon refraction of the core assembly 140 into the catheter110, as shown in FIGS. 10 and 12.

Further, in some embodiments, the first section 420 of the distal cover400 can radially overlap with the distal end 204 of the stent 200 at anoverlap point 820 along the core member 160. As illustrated in FIGS.5A-B and 12, the overlap point 820 can be located along the core member160 proximal to the tip assembly 180. In some embodiments, the overlappoint 820 can be spaced about 5 mm to about 12 mm from the proximal endof the distal tip structure 182. In some embodiments, the overlap point820 can be spaced about 6 mm to about 10 mm from the proximal end of thedistal tip structure 182. Further in some embodiments, the overlap point820 can be spaced about 8 mm from the proximal end of the distal tipstructure 182. The overlap point 820 can be located at or near thedistal end 812 of the intermediate portion 814 of the core member 160,or at any location along the core member 160 that underlies an overlapof the (first section 420 of the) distal cover 400 over the stent 200when the core assembly 140 is in its pre-deployment configuration shownin FIGS. 1-5B and 13A-13B. Additionally, in some such embodiments, inthe second orientation, the first section 420 of the distal cover 400 nolonger overlaps with the (distal end 204 of) the stent 200 at theoverlap point 820 (and the first section 420 can be located distally ofsuch location), upon refraction of the core assembly 140 into thecatheter 110, as shown in FIGS. 10 and 12.

In the second orientation, as shown in FIGS. 7A-8, there is no longerradial overlap of the stent 200 and the cover 400 at the overlap point820 or at the distal end 812 of the intermediate section 814. Thus,after disengagement of the distal cover 400 from the stent 200, the coreassembly 140 can be proximally withdrawn into the catheter 110 and thedistal cover 400 will generally extend in a distal direction away fromthe overlap point 820. As also shown in FIGS. 9-10, at such time thatthe stent 200 is resheathed or withdrawn into the catheter 110 afterpartial expansion, the stent 200 and the distal cover 400 will notoverlap at the overlap point 820. Thus, the distal cover 400 will notoverlap the stent 200 or the overlap point 820 after at least partialexpansion of the stent 200 when the core assembly 140 is withdrawn intothe catheter 110. Further, once the distal cover 400 is disengaged, theintermediate portion 814 of the core member 160 can be positionedradially adjacent to the distal end 114 of the catheter 110 with thedistal cover 400 being positioned outside of the radial space 804between the intermediate portion 814 and the catheter 110. Accordingly,the movement and configuration of the distal cover 400 can enable thecore assembly 140 to provide radial clearance between the core member160 or the intermediate portion 814 and the catheter 110 forfacilitating resheathing of the core member 160, as shown in FIGS. 9-10and 12.

The distal cover can be coupled relative to the core member. The distalcover can be bonded to the core member and/or the tip assembly 180 ofthe core assembly. In some embodiments, the distal cover can be threadedinto a coil of the tip assembly 180. In the embodiment shown in FIG. 5A,the distal cover 400 can be coupled directly to the distal tip structure182 and indirectly coupled to the core member 160. In the embodiment ofFIG. 5A, the distal tip structure 182 is rigidly coupled to the coremember 160. However, the distal tip structure 182 can also be movablerelative to the core member 160, to provide relative rotation or slidingalong the core member 160, as discussed below with regard to FIG. 5C.

For example, the distal cover 400 and/or the distal tip structure 182can be configured to rotate about the core member 160. For example, anend of the distal cover 400 can be rotatably coupled with respect to thecore member 160. Thus, the stent 200 can be configured to rotate aboutthe core member 160 at least in part by virtue of the rotatable couplingof the distal cover 400. Accordingly, in some embodiments, the stent canrotate with respect to the core member 160 while minimizing anytorsional stresses on the stent.

In the embodiment of FIG. 5A, the distal cover 400 comprises a shrinktube 460 configured to shrink and adhere the second section 440 to thedistal tip structure 182. Alternatively, the second section 440 of thedistal cover 400 can be coupled to the distal tip structure 182 viaother devices or attachment means, including, but not limited tomechanical fasteners, welding techniques, adhesives, heat bonding,combinations thereof, or the like. In yet another alternative, thesecond section 440 can be coupled directly to a distal portion or thedistal end 164 of the core member 160 itself using any suitableattachment.

In some embodiments, the distal tip structure 182 can comprise at leastone member that can be oriented generally transverse or parallel to thecore member. For example, the tip structure 182 can comprise a coil(s),a circumferentially-extending band(s) of material, a clamp(s), and/orother structures that can pass smoothly within a vessel at the distalportion of the core member. Further, the at least one member cancomprise at least one segment of the coil or other structure. Accordingto some embodiments, the distal cover 400 can be coupled to the distaltip structure 182 by virtue of forming an enclosure that encloses the atleast one member. For example, the distal cover 400 can form anenclosure that encloses at least one coil segment of the distal tipstructure 182 by virtue of at least partially wrapping around thesegment.

FIG. 5B illustrates another embodiment of a core assembly 140′. The coreassembly 140′ comprises a core member 160′, a distal tip assembly 180′(having a distal tip structure 182′ in the form of a coil), and a distalcover 400′. The distal cover 400′ comprises a free first section 420′and a fixed second section 440′. The second section 440′ is attached tothe coil of the distal tip structure 182′ by passing or being loopedbetween adjacent windings of the coil (or otherwise through a side ofthe coil or around one or more windings of the coil), as illustrated.The second section 440′ can comprise a looped portion 442′ that extendsbetween the adjacent coil windings and proximally back into contact withanother portion of the second section 440′. The overlapping aspects ofthe looped portion 442′ and the second section 440′ can be fused orotherwise joined or adhered to each other to securely attach the distalcover 400′ to the distal tip structure 182′. Other components of thecore assembly 140′ and catheter 110′ are labeled similarly to FIG. 5A,as illustrated.

FIG. 5C is a rear perspective view of a distal cover 400″. The distalcover 400″ can be similar in structure, function and method of use tothe distal cover 400 (e.g., as shown in FIG. 5A) and/or the distal cover400′ (e.g., as shown in FIG. 5B), but with additional or substitutedstructures, functions and uses as described herein. The distal cover400″ can be used in place of the distal covers 400/400′ in constructingany embodiment of the core assembly 140. The distal cover 400″ can becoupled to a distal tip assembly 180″ in a manner similar to thatillustrated in FIG. 5B. However, in this embodiment, the distal tipassembly 180″ comprises a distal tip structure 182″ that islongitudinally and/or rotatably movable relative to the core member160″.

In some embodiments, the core member 160″ can comprise an proximal stop430″ and a distal stop 432″. The proximal stop 430″ and the distal stop432″ can be configured to limit the range of sliding movement of thedistal tip structure 182″. The proximal stop 430″ and the distal stop432″ can be spaced apart from each other along the core member 160″ by adistance that permits longitudinal movement of the tip structure 182″relative to the core member 160″. In some embodiments, the stops 430,432 permit substantially zero longitudinal movement of the tip structure182″ and cover 400″ but do allow these components to rotate about thecore member 160″. The distal tip structure 182″ can comprise an innerlumen that receives the core member 160″ therein such that the distaltip structure 182″ can slide and/or rotate relative to the core member160″. For example, some embodiments of the distal tip structure 182″ cancomprise a coil. Thus, the distal cover 400″ can rotate and/or sliderelative to the core member 160″. Such movement can allow the distalcover 400″ to move or rotate with the stent during delivery to reducestresses and pushing force as the core assembly 140″ traverses thevasculature of the patient.

The distal cover can be one or more strips, wings, or elongate portionsthat are coupled to the tip assembly and/or core member of the coreassembly. In some embodiments, the distal cover comprises no more thantwo elongate strips, wings, or elongate portions. The strips, wings, orelongate portions can be formed as separate components that are coupledto the core assembly. Further, the strips, wings, or elongate portionscan also be formed from a single, continuous piece of material that iscoupled to the core assembly. The strips, wings, or elongate portionscan have free first ends, as well as second ends that are coupled to thecore assembly. The free first ends can cover at least a portion of thestent distal portion during delivery of the stent. Further, when thecore assembly is proximally withdrawn into the catheter, the strips,wings, or elongate portions can be everted, such that free first ends ofthe strips, wings, or elongate portions are drawn together distal to thesecond ends.

For example, the distal cover can be manufactured or otherwise cut froma tube of the material selected for the distal cover. As illustrated inFIGS. 5-6, in some embodiments, the first section 420 may be formed asmultiple longitudinal strips cut from the tube, and the second section440 may be an uncut length of the tube. Accordingly, the tubular secondsection 440 and the proximally extending strips of the first section 420may form a single, integral device or structure.

In some embodiments, the distal cover 400 may comprise a tube and thefirst section 420 can include two or more semi-cylindrical or partiallycylindrical strips or tube portions separated by a corresponding numberof generally parallel, longitudinally oriented cuts or separationsformed or otherwise positioned in the sidewall of the tube. Therefore,when in the pre-expansion state, as shown in FIGS. 1, 2, 4, 5 and 6, thefirst section 420 may generally have the shape of a longitudinally splitor longitudinally slotted tube extending or interposed radially betweenthe outer surface 208 of the stent 200 and the inner surface 118 of thecatheter 110.

In various embodiments, the strips, wings, or elongate portions of thefirst section 420 may collectively span substantially the entirecircumference of the outer surface 208 of the stent 200 (e.g., where thecuts between the strips are splits of substantially zero width), or besized somewhat less than the entire circumference (e.g., where the cutsbetween the strips are slots having a nonzero width). In accordance withsome embodiments, the width of the strips, wings, or elongate portionsof the first section 420 can be between about 0.5 mm and about 4 mm. Thewidth can be about 0.5 mm to about 1.5 mm. In accordance with someembodiments, the width can be about 1 mm.

The strips, wings, or elongate portions of the first section 420 canalso extend longitudinally over at least a portion of the distal portionof the stent. In some embodiments, the first section 420 can extendbetween about 1 mm and about 3 mm over the distal portion of the stent.Further, the first section 420 can also extend between about 1.5 mm andabout 2.5 mm over the distal portion of the stent. In accordance withsome embodiments, the first section 420 can extend about 2 mm over thedistal portion of the stent.

The first section 420 and the second section 440 can define a totallength of the distal cover 400. In some embodiments, the total lengthcan be between about 4 mm and about 10 mm. The total length can also bebetween about 5.5 mm and about 8.5 mm. In some embodiments, the totallength can be about 7 mm.

The strips of the first section 420 may be of substantially uniformsize. For example, the first section 420 can comprise two stripsspanning approximately 180 degrees each, three strips spanningapproximately 120 degrees each, four strips spanning approximately 90degrees each, or otherwise be divided to collectively cover all or partof the circumference of the stent, etc. Alternatively, the strips maydiffer in angular sizing and coverage area without departing from thescope of the disclosure. In one embodiment, only two strips or tubeportions are employed in the first section 420. The use of only twostrips can facilitate radial expansion, distal movement and/or fold-overor everting of the first section 420, as discussed herein, whileminimizing the number of free or uncontained strips in the blood vessellumen and any potential for injuring the vessel by virtue of contactbetween a strip and the vessel wall.

In accordance with some embodiments, at or near the distal end 204 ofthe stent 200, the first section 420 of the distal cover 400 may beconfigured to evert or otherwise fold over and/or within itself, therebycreating a folded portion 480 extending or interposed radially betweenthe outer surface 208 of the stent 200 and the inner surface 118 of thecatheter 110, as shown in FIGS. 5A-B. As illustrated, the folded portion480 can have an outer layer 482 and an inner layer 484, where the outerlayer 482 is radially adjacent the inner surface 118 of the catheter 110and the inner layer 484 is radially adjacent the outer surface 208 ofthe stent 200. In such embodiments, the configuration of the inner layer484, which is radially adjacent to the outer surface 208 of the stent200, can advantageously facilitate expansion of the stent 200 becausethe stent 200 would not need to slide along the inner layer 484.Instead, the inner layer 484 can be everted as the stent expands,thereby reducing any friction between the stent 200 and the distal cover400.

Further, in some embodiments, the distal cover 400 can be configured tofold over itself, in a manner opposite to that shown in FIGS. 5A-B, suchthat layer 482 is the inner layer and layer 484 is the outer layer. Inother embodiments, the first section 420 is not folded, everted, oreverted at all, when in the first or pre-expansion configuration.

The distal cover can be manufactured using a lubricious and/orhydrophilic material such as PTFE or Teflon®, but may be made from othersuitable lubricious materials or lubricious polymers. The distal covercan also comprise a radiopaque material. For example, one or more stripsof Teflon® can be coupled to the core member or distal tip structure inorder to form the distal cover. The distal cover can define a thicknessof between about 0.0005″ and about 0.003″. In some embodiments, thedistal cover can be one or more strips of PTFE having a thickness ofabout 0.001″. The material of the distal cover can also be attached bymeans of another material, such as the shrink tube 460, fitted aroundthe perimeter of the distal cover. The shrink tube 460 can define aradial thickness of between about 0.001″ and about 0.002″. Someembodiments, the radial thickness of the shrink tube is about 0.0015″(based on a tubular shape having an inner diameter of about 0.016″ hadan outer diameter of about 0.019″). Thus, the radial clearance betweenthe distal cover (when everted) and the inner surface of the cathetercan be about 0.002″ and about 0.004″.

When the core assembly 140 is being withdrawn, as shown in FIG. 10 or12, the distal cover 400 can extend distally through the annular spacebetween the distal tip of the core member 160 and the inner surface 118of the catheter 110 and provide a clearance therebetween. The clearancebetween the inner surface 118 and the distal cover 400 (when urgedagainst the distal tip of the core member 160) can be equal to orgreater than the radial clearance between the outer surface of theconstraining member 320 and the inner surface 118 of the catheter 110.Thus, as noted above, if the inner diameter of the catheter 110 is about0.030″ and the outer diameter of the constraining member 320 is about0.025″, the radial clearance between the inner surface 118 and thedistal cover 400 would at least about 0.0025″. Further, as also notedherein, the outer diameter of the distal tip structure 182 can be about0.015″.

In operation, the distal cover 400, and in particular the first section420 or the folded portion 480, can generally cover and protect thedistal end 204 of the stent 200 as the stent 200 is moved distallywithin the catheter 110. The distal cover 400 may serve as a bearing orbuffer layer that, for example, inhibits filament ends 212 of the distalend 204 of the stent 200 (shown schematically in FIGS. 5A-B) fromcontacting the inner surface 118 of the catheter 110, which could damagethe stent 200 and/or catheter 110, or otherwise compromise thestructural integrity of the stent 200. Since the distal cover 400 may bemade of a lubricious material, the distal cover 400 may exhibit a lowcoefficient of friction that allows the distal end 204 of the stent 200to slide axially within the catheter 110 with relative ease. Thecoefficient of friction between the distal cover and the inner surfaceof the catheter can be between about 0.02 and about 0.4. For example, inembodiments in which the distal cover and the catheter are formed fromTeflon®, the coefficient of friction can be about 0.04. Such embodimentscan advantageously improve the ability of the core assembly to passthrough the catheter, especially in tortuous vasculature.

Structures other than the herein-described embodiments of the distalcover 400 may be used in the core assembly 140 to cover the distal endof the stent 200. For example, a protective coil or other sleeve havinga longitudinally oriented, proximally open lumen may be employed.Suitable such protective coils include those disclosed in theincorporated U.S. Patent Application Publication No. 2009/0318947 A1.

Further, as also noted herein, some embodiments can be configured suchthat the distal tip assembly (e.g., the distal tip structure 182) isrotatable and/or axially movable relative to the core member 160.Similarly, in embodiments wherein the distal tip assembly comprises onlythe distal cover 400, although the distal cover 400 can be fixedlycoupled relative to the core member 160, the distal cover 400 can alsobe rotatably and/or axially movably coupled relative to the core member160. Further, when the distal tip assembly comprises both the distal tipstructure and the distal cover, the distal tip assembly can be rotatablyand/or axially movably coupled relative to the core member; however, thedistal tip assembly can also be fixedly coupled to the core member.Thus, as similarly noted above, some embodiments of the distal cover canallow the core member to rotate freely relative to the distal cover andthe stent, thereby avoiding exertion of torsional forces on the stentand/or distal cover as the core assembly is moved through the catheterto the treatment site.

As noted, embodiments of the distal cover can provide variousadvantages. For example, the use of the distal cover can allow the stentholding assembly to be easily urged toward the treatment site within thecatheter. This can advantageously reduce the delivery force required tomove the core assembly through the catheter. In addition, the distal tipassembly can be compactly configured and therefore provide excellentmaneuverability as the stent holding assembly moves through tortuousanatomy. Further, a flexible distal cover such as the depicted distalcovers 400, 400′, 400″ can also allow the distal portion of the stent toopen or expand radially immediately as the distal portion of the stentexits the catheter. The distal cover can be easily urged away from thefirst or encapsulating position or configuration such that the expansionof the stent is not hindered and expansion can be predictable to theclinician. Where employed, this can be a significant improvement overprior art devices that used a relatively rigid tube, such as a coil todistally restrain a distal end of the stent, which could impede or makeunpredictable the proper expansion or deployment of an occluding device,especially large diameter occluding devices.

Further, where the first portion 420 is flexible, evertible, and/orprovides a minimal cross-section, the distal tip assembly can be easilyrecaptured within the catheter to facilitate resheathing for refractionof the core assembly into the catheter. Thus, the catheter can remain inplace and the entire core assembly can be withdrawn therefrom. This canenable the clinician to “telescope” one or more other occluding devices(e.g., delivering more than one occluding device such that it overlapswith another occluding device) without having to remove the catheter,saving time and reducing trauma to the patient.

FIGS. 1 and 7-12 depict some embodiments and methods of use of the stentdelivery system 100. First, the catheter 110 can be inserted into thepatient's vasculature via a percutaneous access technique or othersuitable method of access. The distal end 114 of the catheter 110 isthen advanced to a treatment site or location in the blood vessel 102.The blood vessel 102 may comprise a vein or artery, such as an artery ina brain or within a cranium of the patient. As previously mentioned, thecatheter 110 can comprise a microcatheter. A guide catheter can be usedinstead of or in addition to the catheter 110; for example, the guidecatheter can first be placed in the vasculature so that it extends partor all of the way to the treatment site and a microcatheter or othercatheter then inserted through the guide catheter to the treatment site.

The treatment location may be near an aneurysm (not shown) formed in awall of the blood vessel 102, and advancing the catheter 110 to thetreatment location may include advancing the distal end 114 and/ordistal opening 120 to a location that is distal of the aneurysm. Suchadvancement of the catheter 110 may include advancing the distal end 114and/or distal opening 120 distally across the ostium or neck of theaneurysm, to the location in the vessel 102 distal of the aneurysm.

Once the catheter 110 has been inserted, it may extend proximally fromthe distal end 114 and/or distal opening 120 at the treatment location,through the vascular access site, to the proximal end 112 and/or hub 122which are preferably situated outside the patient's body.

After the catheter 110 has been placed, the core assembly 140 (with thestent 200 carried thereby) can be inserted, distal end first, into thelumen 116 of the catheter 110 via the hub 122 and/or proximal end 112.Where the distal portion of the core assembly 140 is initially containedwithin an introducer sheath (not shown), the introducer sheath can beinserted partway into the catheter lumen 116 and the core assembly 140is advanced distally through the introducer sheath until the distalportion and stent 200 exit the distal end of the introducer sheath andpass into (direct contact with) the lumen 116 of the catheter 110. Thecore assembly 140 and stent 200 are at that point disposed in thecatheter 110 generally as depicted in FIG. 1, but in a proximal portionof the catheter 110. In particular, the stent 200 and distal portion ofthe core assembly 140 can be positioned in the lumen 116 of the catheter110, with the proximal end 202 of the stent 200 received in theconstraining member 320 and the remaining portions of the stent 200extending distally and generally in contact with the inner surface 118of the catheter except where the first section 420 of the distal cover400 is extending or interposed radially between the distal end 204 ofthe stent 200 and the inner surface 118 of the catheter 110. Further,the core member 160 and constraining member 320 can extend proximally ofthe proximal end 112 and/or hub 122 of the catheter 110 to a locationoutside of the patient's body, so that the coupling 360 and proximalends 162, 322 of the core member 160 and constraining member 320 can beeasily accessed.

Next, the core assembly 140 with the stent 200 can be axially advanceddistally within the lumen 116 of the catheter 110, toward the distal end114 of the catheter 110 and treatment location. Generally, duringadvancement of the core assembly 140 in the catheter 110, theconstraining member 320 and the protruding member 340 can secure, grip,or engage the stent 200 to facilitate urging the stent distally throughthe catheter 110, substantially without transmitting any securementforces to the catheter 110 or otherwise independently of the catheter110. The constraining member 320 and the protruding member 340 cansecure, grip, or engage the stent 200 during distal advancement throughthe catheter 110 without relative axial motion between the constrainingmember 320 and the protruding member 340, while the constraining member320, the protruding member 340, and the stent 200 move distally relativeto the catheter 110 and the vasculature.

As the stent 200 and distal cover 400 are advanced toward the distal end114 and treatment location, the first section 420 of the distal cover400 remains extending or interposed radially between the outer surface208 and/or distal end 204 of the stent 200 and the inner surface 118 ofthe catheter 110. Thus, the distal cover 400 may inhibit the distal end204 of the advancing stent 200 (e.g., the filament ends 212 thereof)from damaging, abrading, or gouging the catheter 110, and from therebyimpeding progress of the stent 200 along the catheter 110. This may, inturn, avoid damage to the stent 200 such as by longitudinal compressionresulting from high friction generated between the distal end 204 of thestent 200 and the catheter 110 while distally directed force is appliedto the proximal portions of the stent 200.

Where the treatment location is near an aneurysm and the distal end 114and/or distal opening 120 of the catheter 110 has been advanced to alocation that is distal of the aneurysm, advancement of the coreassembly 140 with the stent 200 toward the distal end 114 and treatmentlocation can include advancing the distal portion of the core assembly140 and the distal end 204 of the stent 200 distally through thecatheter 110 across the ostium or neck of the aneurysm, to a location inthe vessel 102 distal of the aneurysm.

To begin expansion of the stent 200 (see FIG. 7, i.e. FIGS. 7A-7C), thecore assembly 140 may be held stationary and the catheter 110 may bewithdrawn proximally over the stent 200 and distal portion of the coreassembly 140, until the distal end 114 of the catheter 110 is even withor proximal of the distal end 324 of the constraining member 320 or evenwith or proximal of the proximal end 202 of the stent 200 or proximalretaining member 220, as shown in FIG. 8. (Optionally, the core assemblyand stent can be advanced distally while performing this step, insteadof or in addition to withdrawal of the catheter.) As a result, the stent200 (except for the portion retained in the constraining member 320) canbe released and permitted to expand into engagement with the inner wallof the blood vessel 102, as shown in FIG. 8. Some embodiments of thestent 200 (such as certain braided stents) can shorten axially whileexpanding radially. As a result of (i) any axial foreshortening of thestent 200, (ii) radial expansion of the stent 200, and/or (iii) radialexpansion of the distal cover 400 in response to radial expansion of thestent 200, the strips or tube portions of the first section 420 of thedistal cover 400 can disengage from contact with the distal end 204 ofthe stent 200, while in some embodiments separating and moving radiallyoutward as well.

In some embodiments, as the distal cover 400 disengages from the stent,it unfurls or otherwise unravels from its folded configuration 480 (seeFIGS. 7-8). Once the distal cover 400 disengages or unravels, it nolonger covers the distal end 204 of the stent 200; instead, its firstsection 420 is now spaced distally from the stent distal end 204 asshown in FIGS. 7-8. In this state, the strips or tube portions formingthe proximal end can be free or unconfined within the lumen of the bloodvessel 102. As similarly noted above, the strips or tube portions canhave free first ends, as well as second ends that are coupled to thecore assembly 140. The free first ends can cover at least a portion ofthe stent distal portion during delivery of the stent. Further, when thestent is expanded and/or the core assembly 140 is proximally withdrawninto the catheter, the strips or tube portions can be everted, such thatfree first ends of the strips, wings, or elongate portions are drawntogether distal to the second ends thereof.

The pullback of the catheter 110 (and/or distal movement of the coreassembly 140) and expansion of the stent 200 may be done in multiplediscrete steps. For example, the catheter 110 may initially be pulledback proximally only part of the way to the location depicted in FIGS.7A-C, and only the distal portion 204 of the stent 200 expanded intoengagement with the vessel wall. Such initial partial expansionfacilitates anchoring the distal portion of the stent in the vessel 102,which in turn facilitates longitudinal stretching or compression of thestent 200 as desired by the clinician during or prior to expansion ofthe remaining portions of the stent 200 into the vessel 102. Initialpartial expansion can also facilitate confirmation by the clinician thatthe distal portion of the stent 200 has “landed” in the desired locationin the vessel 102 (e.g., distal of the neck or ostium of any aneurysmformed in the vessel wall) prior to expansion of the remaining portionsof the stent 200. Generally, where an aneurysm is present in the vessel102, proper placement of the stent 200 can include positioning a distalportion of the stent 200 in the vessel lumen distal of the aneurysm neckand a proximal portion of the stent in the vessel lumen proximal of theaneurysm neck, such that the stent 200 extends across the neck. Wherethe expanded stent 200 is appropriately configured, it may then performa therapeutic flow-diverting function with respect to the aneurysm.

While the stent delivery system 100 is in the configuration shown inFIG. 8, with the proximal end 202 of the stent 200 retained within theconstraining member 320, the partially expanded stent 200 can beresheathed or retracted proximally into the catheter 110 as shown inFIGS. 9-10. The engagement mechanism, e.g., the constraining member 320and the protruding member 340, can secure, grip, or engage the stent 200to a sufficient degree to permit the catheter 110 to be advanceddistally over the partially expanded stent 200 (and/or the core member160 withdrawn proximally relative to the catheter 110) until the stent200 is again positioned in the lumen 116 of the catheter 110. Thus, theengagement mechanism of the core assembly 140 can exert a proximal forceon the stent 200 as the stent 200 is withdrawn or retracted into thecatheter 110.

FIG. 9 shows a first aspect of a process of resheathing the stent 200,in which the stent 200, including the distal end 204, has been drawninto the lumen 116 of the catheter 110. Because the previouslystent-engaging portion (e.g., the first section 420) of the distal cover400 has moved radially outward from the core member 160 and/or distallyrelative to the core member 160, it does not impede the entrance of thedistal portion and distal end 204 of the stent 200 into the distalopening 120 of the catheter 110 during resheathing. Accordingly, theresheathing process of FIGS. 9-10 can comprise moving the stent 200(including the distal end 204) into the catheter 110 through the distalopening 120 while the previously stent-engaging portion (e.g., the firstsection 420) of the distal cover 400 is in a second, everted, orresheathing configuration in which the stent-engaging portion isdisposed radially outward from the core member 160 and/or the firstsection 420 of the distal cover 400 is disposed distally relative to thecore member 160, the second section 440, and/or the distal tip structure182, in comparison to a first, encapsulating, or delivery configuration(e.g., FIG. 1) of the stent-engaging portion (e.g., the first section420) of the distal cover 400.

While FIG. 9 illustrates an initial aspect of the resheathing process,FIG. 10 shows a second aspect of the resheathing process currently underdiscussion. In this aspect of the process, the core assembly 140 can bemoved further proximally into the catheter 110 (and/or the catheter 110is moved further distally over the core assembly 140) until the distalcover 400 enters the catheter 110 via the distal opening 120. As notedabove, the first section 420 of the distal cover 400 is preferablysufficiently flexible to evert and thereby attain the second, everted,or resheathing configuration shown in FIGS. 9-10. In the second,everted, or resheathing configuration, the first section 420 of thedistal cover 400 can extend generally in a distal direction, away fromthe stent 200, and/or extend distally of the second section 440 of thedistal cover 400. Further, in some embodiments, the first section 420 ofthe distal cover 400 can also radially overlap the distal tip structure182. Instead of or in addition to these aspects of the second, everted,or resheathing configuration, the distal cover 400 can be radially smallenough to extend into the lumen 116 of the catheter 110, eitherpartially as depicted in FIG. 9, or wholly as depicted FIG. 10, and/orthe entire distal cover 400 can be spaced distally from the distal end204 of the stent 200 in the lumen 116 of the catheter 110.

Accordingly, in accordance with some embodiments of methods disclosedherein, when operating the stent delivery system, a clinician can checkthe initial partial expansion of the stent 200 (e.g., as shown in FIGS.7A-8) and, if the initial placement is unsatisfactory or if the initialexpansion of the stent 200 is unsatisfactory, the clinician canrecapture, collapse, withdraw, or resheath the stent 200 into thecatheter 110, as described above with respect to FIGS. 9 and/or 10.After resheathing, the clinician can attempt to land the stent again, asdescribed herein, beginning for example, with the state depicted in FIG.9 or 10, and resulting for example, in the state depicted in FIG. 7A.Resheathing can also be performed, and the stent delivery system 100 andstent 200 removed from the patient entirely, if for example, thedelivery and/or expansion of the stent 200 damages or reveals a defectin, or improper sizing of, the stent 200 or delivery system 100. Afteran initial partial expansion of the stent 200, the depicted coreassembly 140 can optionally be entirely removed with the stent 200 fromthe catheter 110 without need to remove the catheter 110 from the bloodvessel 102. In this manner, access to the treatment site in the bloodvessel 102 can be maintained via the catheter 110 and, if desired,additional attempts to deliver the stent 200 can be made through thecatheter 110.

If the initial expansion of the stent 200 in the vessel 102 issatisfactory, full expansion can be completed to result in the statedepicted in FIG. 11. The coupling 360 is removed, broken, or otherwisedisengaged to permit the constraining member 320 to move relative to thecore member 160. The proximal end 202 of the stent 200 may then bereleased from the constraining member 320 and the protruding member 340by holding the core member 160 stationary and withdrawing theconstraining member 320 proximally relative to the core member 160 andthe stent 200 until the distal end 324 is approximately even with theproximal retaining member 220, or otherwise proximal of the proximal end202 of the stent 200. (If the distal end 114 of the catheter 110 has notyet been withdrawn to a location proximal of the proximal end 202 of thestent 200, that can be done as well.) No longer constrained by theconstraining member 320 and the protruding member 340, the proximal end202 of the stent 200 can now expand into contact with the wall of thevessel 102, as shown FIG. 11. (Note that until this point, according toan aspect of some embodiments, the partially expanded stent 200 had beenfully resheathable.) Where the vessel 102 includes an aneurysm, theproximal end 202 is preferably located in the vessel 102 proximal of theaneurysm neck following expansion.

Following full expansion of the stent 200, the core assembly 140 can bedrawn back into the catheter 110, as shown in FIG. 12. Both the catheter110 and core assembly 140 can be withdrawn from the patient, eithersimultaneously or sequentially. However, when the stent has beensuccessfully released, the core assembly 140 can also be entirelyremoved from the catheter 110, with the catheter 110 remaining in place,and a second core assembly can be inserted into the lumen. The secondcore assembly can be configured to deliver a second stent to thetreatment site in order to perform, e.g., a telescoping procedure.

In another embodiment of a method, the stent 200 can be initiallypartially expanded (e.g., as shown in FIG. 8) in a blood vessel 102wherein a branch vessel (not shown) joins the blood vessel at a junctionlocated along the portion of the vessel 102 in which the stent 200 hasbeen partially expanded. Patency of the branch vessel can then bechecked by, for example, injecting a contrast agent near the junctionand observing via, for example, fluoroscopy whether the agent can flowfrom the vessel 102 into the branch vessel. Thus it can be determinedwhether a portion of the stent 102 has occluded the branch vessel. If itappears that the branch vessel has been occluded, the stent 200 can berepositioned within the vessel 102 without resheathing, or the stent 200can be resheathed using any of the techniques discussed herein. Afterresheathing, the stent 200 can be partially expanded again, and branchvessel patency checked again.

In the present disclosure, numerous references are made to moving thecatheter 110 axially over the core assembly 140, and moving the coreassembly 140 axially within the catheter 110. Except where specificallynoted to the contrary, all such references to one form of this relativemovement should be understood to include the other as an alternative.

As discussed above, the stent delivery system 100 can also be configuredto allow the clinician to control the articulation and delivery of thesystem by steering a portion of the system. For example, referring toFIGS. 13A-B, the stent delivery system 100 can optionally include asteerable tip assembly 900. The steerable tip assembly 900 can allow aclinician to avoid perforating or abrading the vessel wall of a vesselbifurcation or a sharp turn in the vessel while performing theprocedure. As noted above, in some embodiments, the steerable tipassembly 900 can include the core member 160, which can have acurvilinear distal end 164. Optionally, in some embodiments, thesteerable tip assembly 900 can be employed with one or more protrudingmembers 340 that are rotatably mounted on the core member 160.Accordingly, the core member 160 can be configured to be steerableduring stent expansion, or when the stent is in the catheter orpartially expanded within the vessel by being rotatable relative to thestent 200, the catheter 110, and/or other components of the stentdelivery system 100.

In use, the clinician can advance the stent delivery system 100 to thetreatment location axially within the vessel 102. In preparation fordeployment and expansion of the stent 200, the clinician can survey thesurrounding vasculature of the treatment site and determine whetherthere is a risk of having the distal end of the core member abrade orperforate a vessel wall as the core member is advanced distally asanticipated during stent expansion or during advancement of the system100 to the treatment location. Generally, the core member 160 and thedistal tip assembly 180 are often advanced distally in the course ofexpanding a stent, so the anticipated distal movement can be thatresulting from stent deployment near a bifurcation or sharp turn in thevessel. If there is a risk that abrasion or perforation of a vessel maytake place, the clinician can carefully land the stent and thereafter(or beforehand) rotate the core member to reorient or redirect thedistal end or point of the core member towards the pathway of the vesseland away from the vessel wall.

The risk of abrasion or perforation can be substantially greater whenthe treatment location is adjacent to a bifurcation or sharp turn in thevessel. For example, FIGS. 13A-B illustrate a scenario in which an apex940 of a bifurcation 942 lies in the anticipated path of the distal end164 of the core member 160. As such, if the distal end 164 is advanceddistally towards the apex 940 in the position, configuration, ororientation shown in FIG. 13A (and especially if the core member anddistal tip are straight and not curved), there is a likelihood that theapex of the bifurcation will be abraded or perforated by the distal tipof the core member.

However, as shown in FIG. 13B, in order to avoid the abrasion orperforation, the distal end 164 of the core member 160 can be rotated toreorient the curved portion of the distal end 164 toward a lower-riskpathway such as a desired branch vessel. The distal end 164 can beformed from a radiopaque material to make the distal end 164 visibleunder electromagnetic radiation or other imaging, and thereforefacilitate recognition by the clinician of the orientation of the distalend 164 with respect to the surrounding vasculature. Having observed theorientation of the distal end 164, the clinician can determine how to“aim” the distal end 164 of the core member 160 to avoid abrasion orperforation of the vessel wall. For example, in accordance with someembodiments, after determining the appropriate direction after viewingthe position of the distal end 164, the clinician can rotate andreorient the distal end 164 to point the core member 160 in a desired orlower-risk direction by rotating a proximal end of the core member 160.Further, as noted herein, rotation of the core member relative to thestent can allow the clinician to avoid dislodging the stent from thevessel wall after initial expansion of the stent and also avoid abrasionor perforation of the blood vessel. In this manner, the stent deliverysystem can advantageously allow a clinician to steer and control thearticulation of the stent delivery system to ensure that the vesselsadjacent to the treatment site are not damaged as the stent is deployedand the core assembly 140 is advanced.

Information regarding additional embodiments of the stent deliverysystem 100, and additional details and components that can optionally beused or implemented in the embodiments of the stent delivery systemdescribed herein, can be found in the above-incorporated U.S. PatentApplication Publications Nos. US 2011/0152998 A1 and US 2009/0318947A1.The stent delivery system 100 disclosed herein can optionally be similarto any of the delivery systems disclosed in these publications, exceptas further described herein.

The apparatus and methods discussed herein are not limited to theexpansion and use of an stent or occluding device within any particularvessels, but may include any number of different types of vessels. Forexample, in some aspects, vessels may include arteries or veins. Thevessels may have bifurcations and/or sharp turns. In some aspects, thevessels may be suprathoracic vessels (e.g., vessels in the neck orabove), intrathoracic vessels (e.g., vessels in the thorax), subthoracicvessels (e.g., vessels in the abdominal area or below), lateral thoracicvessels (e.g., vessels to the sides of the thorax such as vessels in theshoulder area and beyond), or other types of vessels and/or branchesthereof.

In some aspects, the suprathoracic vessels may comprise at least one ofintracranial vessels, cerebral arteries, and/or any branches thereof.For example, the suprathoracic vessels may comprise at least one of acommon carotid artery, an internal carotid artery, an external carotidartery, a middle meningeal artery, superficial temporal arteries, anoccipital artery, a lacrimal (ophthalmic) artery, an accessory meningealartery, an anterior ethmoidal artery, a posterior ethmoidal artery, amaxillary artery, a posterior auricular artery, an ascending pharyngealartery, a vertebral artery, a left middle meningeal artery, a posteriorcerebral artery, a superior cerebellar artery, a basilar artery, a leftinternal acoustic (labyrinthine) artery, an anterior inferior cerebellarartery, a left ascending pharyngeal artery, a posterior inferiorcerebellar artery, a deep cervical artery, a highest intercostal artery,a costocervical trunk, a subclavian artery, a middle cerebral artery, ananterior cerebral artery, an anterior communicating artery, anophthalmic artery, a posterior communicating artery, a facial artery, alingual artery, a superior laryngeal artery, a superior thyroid artery,an ascending cervical artery, an inferior thyroid artery, athyrocervical trunk, an internal thoracic artery, and/or any branchesthereof. The suprathoracic vessels may also comprise at least one of amedial orbitofrontal artery, a recurrent artery (of Heubner), medial andlateral lenticulostriate arteries, a lateral orbitofrontal artery, anascending frontal (candelabra) artery, an anterior choroidal artery,pontine arteries, an internal acoustic (labyrinthine) artery, ananterior spinal artery, a posterior spinal artery, a posterior medialchoroidal artery, a posterior lateral choroidal artery, and/or branchesthereof. The suprathoracic vessels may also comprise at least one ofperforating arteries, a hypothalamic artery, lenticulostriate arteries,a superior hypophyseal artery, an inferior hypophyseal artery, ananterior thalamostriate artery, a posterior thalamostriate artery,and/or branches thereof. The suprathoracic vessels may also comprise atleast one of a precentral (pre-Rolandic) and central (Rolandic)arteries, anterior and posterior parietal arteries, an angular artery,temporal arteries (anterior, middle and posterior), a paracentralartery, a pericallosal artery, a callosomarginal artery, a frontopolarartery, a precuneal artery, a parietooccipital artery, a calcarineartery, an inferior vermian artery, and/or branches thereof.

In some aspects, the suprathoracic vessels may also comprise at leastone of diploic veins, an emissary vein, a cerebral vein, a middlemeningeal vein, superficial temporal veins, a frontal diploic vein, ananterior temporal diploic vein, a parietal emissary vein, a posteriortemporal diploic vein, an occipital emissary vein, an occipital diploicvein, a mastoid emissary vein, a superior cerebral vein, efferenthypophyseal veins, infundibulum (pituitary stalk) and long hypophysealportal veins, and/or branches thereof.

The intrathoracic vessels may comprise the aorta or branches thereof.For example, the intrathoracic vessels may comprise at least one of anascending aorta, a descending aorta, an arch of the aorta, and/orbranches thereof. The descending aorta may comprise at least one of athoracic aorta, an abdominal aorta, and/or any branches thereof. Theintrathoracic vessels may also comprise at least one of a subclavianartery, an internal thoracic artery, a pericardiacophrenic artery, aright pulmonary artery, a right coronary artery, a brachiocephalictrunk, a pulmonary trunk, a left pulmonary artery, an anteriorinterventricular artery, and/or branches thereof. The intrathoracicvessels may also comprise at least one of an inferior thyroid artery, athyrocervical trunk, a vertebral artery, a right bronchial artery, asuperior left bronchial artery, an inferior left bronchial artery,aortic esophageal arteries, and/or branches thereof.

In some aspects, the intrathoracic vessels may also comprise at leastone of a right internal jugular vein, a right brachiocephalic vein, asubclavian vein, an internal thoracic vein, a pericardiacophrenic vein,a superior vena cava, a right superior pulmonary vein, a leftbrachiocephalic vein, a left internal jugular vein, a left superiorpulmonary vein, an inferior thyroid vein, an external jugular vein, avertebral vein, a right highest intercostal vein, a 6th rightintercostal vein, an azygos vein, an inferior vena cava, a left highestintercostal vein, an accessory hemiazygos vein, a hemiazygos vein,and/or branches thereof.

In some aspects, the subthoracic vessels may comprise at least one ofrenal arteries, inferior phrenic arteries, a celiac trunk with commonhepatic, left gastric and splenic arteries, superior suprarenalarteries, a middle suprarenal artery, an inferior suprarenal artery, aright renal artery, a subcostal artery, 1st to 4th right lumbararteries, common iliac arteries, an iliolumbar artery, an internal iliacartery, lateral sacral arteries, an external iliac artery, a testicular(ovarian) artery, an ascending branch of deep circumclex iliac artery, asuperficial circumflex iliac artery, an inferior epigastric artery, asuperficial epigastric artery, a femoral artery, a ductus deferens andtesticular artery, a superficial external pudendal artery, a deepexternal pudendal artery, and/or branches thereof. The subthoracicvessels may also comprise at least one of a superior mesenteric artery,a left renal artery, an abdominal aorta, an inferior mesenteric artery,colic arteries, sigmoid arteries, a superior rectal artery, 5th lumbararteries, a middle sacral artery, a superior gluteal artery, umbilicaland superior vesical arteries, an obturator artery, an inferior vesicaland artery to ductus deferens, a middle rectal artery, an internalpudendal artery, an inferior gluteal artery, a cremasteric, pubic(obturator anastomotic) branches of inferior epigastric artery, a leftcolic artery, rectal arteries, and/or branches thereof.

In some aspects, the lateral thoracic vessels may comprise at least oneof humeral arteries, a transverse cervical artery, a suprascapularartery, a dorsal scapular artery, and/or branches thereof. The lateralthoracic vessels may also comprise at least one of an anteriorcircumflex humeral artery, a posterior circumflex humeral artery, asubscapular artery, a circumflex scapular artery, a brachial artery, athoracodorsal artery, a lateral thoracic artery, an inferior thyroidartery, a thyrocervical trunk, a subclavian artery, a superior thoracicartery, a thoracoacromial artery, and/or branches thereof.

In some embodiments, the delivery system 100 can include an expandableoccluding device (e.g., stent 200) configured to be placed across ananeurysm. The occluding device can be delivered through the distalportion of the catheter, out a distal tip assembly, and into thevasculature adjacent an aneurysm in, for example, the middle cerebralartery. A proximal portion of the catheter can remain partially orentirely within a guiding catheter during delivery, and an intermediateportion, taper portion, and distal portion of the catheter can extenddistally of the guiding catheter. The occluding device can be releasedat the target location and can be used to occlude blood flow into theaneurysm. The catheter can be used to reach target locations (e.g.,aneurysms) located elsewhere in the body as well, include but notlimited to other arteries, branches, and blood vessels such as thosedescribed above.

The apparatus and methods discussed herein are not limited to thedeployment and use of an occluding device or stent within the vascularsystem but may include any number of further treatment applications.Other treatment sites may include areas or regions of the body such asorgan bodies.

Although the detailed description contains many specifics, these shouldnot be construed as limiting the scope of the subject technology butmerely as illustrating different examples and aspects of the subjecttechnology. It should be appreciated that the scope of the subjecttechnology includes other embodiments not discussed in detail above.Various other modifications, changes and variations may be made in thearrangement, operation and details of the method and apparatus of thesubject technology disclosed herein without departing from the scope ofthe present disclosure. Unless otherwise expressed, reference to anelement in the singular is not intended to mean “one and only one”unless explicitly stated, but rather is meant to mean “one or more.” Inaddition, it is not necessary for a device or method to address everyproblem that is solvable by different embodiments of the disclosure inorder to be encompassed within the scope of the disclosure.

What is claimed is:
 1. A method of operating a stent delivery systemwithin a vessel of a patient, comprising: positioning a catheter in thevessel, the catheter having a lumen defining an axis extending between aproximal end and a distal end, such that the catheter distal end is at atreatment site; positioning a core assembly within the catheter lumen,the core assembly having (i) an elongate member comprising a distal end,(ii) an intermediate portion comprising a distal end positioned at themember distal end, (iii) a stent having a distal portion and beingcarried by the intermediate portion, and (iv) a distal cover coupled tothe member distal end, the core assembly being positioned within thelumen such that the intermediate portion distal end is positionedaxially adjacent the catheter distal end with at least a portion of thedistal cover extending in a space within the lumen radially between theintermediate portion distal end and the catheter distal end; distallyadvancing the core assembly relative to the catheter to permit expansionof the stent distal portion, the expansion urging the distal cover awayfrom the intermediate portion; and proximally withdrawing the coreassembly into the catheter such that the intermediate portion ispositioned axially adjacent to the catheter distal end with the distalcover positioned out of the space.
 2. The method of claim 1, whereinduring proximal withdrawal of the core assembly into the catheter, thedistal cover is positioned out of the space to provide a clearancebetween the intermediate portion and the catheter.
 3. The method ofclaim 1, further comprising releasing the stent at the treatment sitewithin the vessel.
 4. The method of claim 3, further comprisingproximally withdrawing the core assembly from the lumen whilemaintaining the catheter distal end in place at the treatment site. 5.The method of claim 4, further comprising inserting a second coreassembly into the lumen, the second core assembly being configured todeliver a second stent at the treatment site.
 6. The method of claim 1,wherein proximally withdrawing the core assembly comprises everting afree first end of the distal cover from a proximally oriented positionto a distally oriented position.
 7. The method of claim 6, wherein thedistal cover is coupled to the core assembly at a distal cover secondend, the first end being positioned distally relative to the second endwhen the distal cover is everted.
 8. A method of operating a stentdelivery system within a blood vessel of a patient, comprising:positioning a catheter in the vessel, the catheter having a lumenextending between a proximal end and a distal end, such that thecatheter distal end is at a treatment site; advancing a core assemblydistally within the catheter, the core assembly having (i) a distalportion, (ii) a distal cover extending from the distal portion, and(iii) a stent having a distal portion and being carried by the coreassembly, the core assembly being advanced within the catheter such thatthe distal cover extends proximally from the distal portion and anannular space between the distal portion and the catheter; distallyadvancing the core assembly relative to the catheter to permit expansionof the stent distal portion, the expansion urging the distal coverradially away from the core assembly; and proximally withdrawing thecore assembly into the catheter such that the distal cover extendsdistally through the annular space.
 9. The method of claim 8, whereinduring proximal withdrawal of the core assembly into the catheter, thedistal cover extends distally through the annular space to provide aclearance between the catheter and an intermediate portion of the coreassembly proximal to the distal cover.
 10. The method of claim 8,wherein proximally withdrawing the core assembly comprises everting afree first end of the distal cover from a proximally oriented positionto a distally oriented position.
 11. The method of claim 10, wherein thedistal cover is coupled to the core assembly at a distal cover secondend, the first end being positioned distally relative to the second endwhen the distal cover is everted.
 12. A method of operating a stentdelivery system within a blood vessel of a patient, comprising:positioning a catheter in the vessel, the catheter having an inner walland a lumen extending between a proximal end and a distal end, such thatthe catheter distal end is at a treatment site; positioning a coreassembly within the lumen, the core assembly comprising a distal coverextending in a proximal direction to at least partially cover a distalportion of a stent supported on the core assembly, at least a portion ofthe distal cover being interposed between the stent distal portion andthe inner wall; distally advancing the stent distal portion beyond thecatheter distal end to permit expansion of the stent distal portion; andproximally withdrawing the core assembly into the lumen, the distalcover being retracted into the lumen in an everted configuration andoriented distally from the core assembly.
 13. The method of claim 12,wherein the distal cover comprises an elongate flexible material havinga first end and a second end, the material being coupled to the coreassembly at the second end, and wherein proximally withdrawing the coreassembly comprises everting the distal cover, such that the first endmoves from a first configuration, in which the first end is locatedproximally relative to the second end, to a second configuration, inwhich the first end is located distally relative to the second end. 14.The method of claim 12, wherein the distal cover comprises a pluralityof elongate flexible strips having first ends and second ends, thesecond ends being coupled to the core assembly, wherein proximallywithdrawing the core assembly comprises everting the distal cover, suchthat the first ends are drawn together distal to the second ends. 15.The method of claim 12, wherein proximally withdrawing the core assemblycomprises retracting the distal cover into the catheter, such that thedistal cover extends distally through an annular space between the coreassembly and the inner wall.